WO2021085487A1 - Nonaqueous electrolyte secondary battery, separator used for same, and method for producing nonaqueous electrolyte secondary battery - Google Patents

Nonaqueous electrolyte secondary battery, separator used for same, and method for producing nonaqueous electrolyte secondary battery Download PDF

Info

Publication number
WO2021085487A1
WO2021085487A1 PCT/JP2020/040485 JP2020040485W WO2021085487A1 WO 2021085487 A1 WO2021085487 A1 WO 2021085487A1 JP 2020040485 W JP2020040485 W JP 2020040485W WO 2021085487 A1 WO2021085487 A1 WO 2021085487A1
Authority
WO
WIPO (PCT)
Prior art keywords
secondary battery
separator
electrolyte secondary
aqueous electrolyte
heat
Prior art date
Application number
PCT/JP2020/040485
Other languages
French (fr)
Japanese (ja)
Inventor
真二 今井
Original Assignee
富士フイルム株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 富士フイルム株式会社 filed Critical 富士フイルム株式会社
Priority to JP2021553660A priority Critical patent/JP7314296B2/en
Publication of WO2021085487A1 publication Critical patent/WO2021085487A1/en
Priority to US17/699,186 priority patent/US20220209362A1/en
Priority to JP2023114337A priority patent/JP2023134622A/en

Links

Images

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0569—Liquid materials characterised by the solvents
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H01M10/0585—Construction or manufacture of accumulators having only flat construction elements, i.e. flat positive electrodes, flat negative electrodes and flat separators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/403—Manufacturing processes of separators, membranes or diaphragms
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • H01M50/417—Polyolefins
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/443—Particulate material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
    • H01M50/451—Separators, membranes or diaphragms characterised by the material having a layered structure comprising layers of only organic material and layers containing inorganic material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
    • H01M50/457—Separators, membranes or diaphragms characterised by the material having a layered structure comprising three or more layers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/46—Separators, membranes or diaphragms characterised by their combination with electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • H01M50/491—Porosity
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present invention relates to a non-aqueous electrolyte secondary battery, a separator used for the non-aqueous electrolyte secondary battery, and a method for manufacturing the non-aqueous electrolyte secondary battery.
  • Non-aqueous electrolyte secondary batteries represented by lithium-ion secondary batteries have high energy density, excellent storage performance, low-temperature operability, etc., and are widely used in portable electronic devices such as mobile phones and laptop computers. There is. In addition, the size of batteries has been increased so that they can be used in transportation equipment such as automobiles, and they are also being used as storage devices for nighttime electric power and electric power generated by natural energy power generation.
  • Patent Document 1 states that in a lithium ion battery, a thermal expansion (sex) capsule is added to a separator infiltrated with an electrolytic solution arranged between a positive electrode and a negative electrode.
  • a thermal expansion (sex) capsule is added to a separator infiltrated with an electrolytic solution arranged between a positive electrode and a negative electrode.
  • the thermally expandable capsule expands when the battery temperature rises, and a space without an electrolytic solution is formed in the separator arranged between the electrodes to physically shut out the movement of lithium ions.
  • Patent Document 2 contains a gas generating agent on the surface or inside of at least one of the positive electrode active material layer, the electrolyte layer, and the negative electrode active material layer, and the temperature of the secondary battery reaches 60 ° C. or higher and lower than 300 ° C.
  • a non-aqueous electrolyte secondary battery characterized in that gas is generated from the gas generating agent is described, and a 1H-tetrazole (gas generating agent) sandwiched between two separators is used instead of the separator.
  • the battery form that was used is also disclosed.
  • the present inventors have made extensive studies in view of the above problems.
  • a heat-expandable capsule is placed between two separators that are in close contact with each other by the action of the electrolytic solution.
  • the heat-expandable capsule can be quickly expanded and shut down in a two-dimensional (planar) manner along the space between the two separators when the battery temperature rises. It was found that even if the thermal melting of the above progresses, it can be sufficiently maintained.
  • a non-aqueous electrolyte secondary battery having a positive electrode, a negative electrode, and a composite separator arranged between the positive electrode and the negative electrode.
  • the composite separator is a non-aqueous electrolyte secondary battery in which a heat-expandable capsule is sandwiched between layers of a laminate composed of at least two separator sheets.
  • the thermal expansion start temperature of the thermal expansion capsule in the non-aqueous electrolyte secondary battery is 5 ° C. or more lower than the thermal melting temperature of the separator sheet sandwiching the thermal expansion capsule, according to [1].
  • Non-aqueous electrolyte secondary battery is 5 ° C. or more lower than the thermal melting temperature of the separator sheet sandwiching the thermal expansion capsule.
  • Secondary battery [5]
  • the composite separator is any one of [1] to [4], wherein the ratio of the total area of the portion where the heat-expandable capsule is arranged to the total area of the composite separator is 50% or less in a plan view.
  • [6] The non-aqueous electrolyte secondary battery according to any one of [1] to [5], wherein the composite separator is in a state of being pressurized in the stacking direction of the separator sheets in the non-aqueous electrolyte secondary battery.
  • the separator sheet constituting the composite separator is a microporous film, and the separator sheets constituting the composite separator are in close contact with each other by the action of the electrolytic solution.
  • the non-aqueous electrolyte secondary battery according to any one of [1] to [7], wherein the separator sheets are adhered to each other around and / or in the vicinity of the composite separator.
  • a composite separator for a non-aqueous electrolyte secondary battery in which a heat-expandable capsule is sandwiched between layers of a laminate composed of at least two separator sheets.
  • a method for producing a non-aqueous electrolyte secondary battery which comprises arranging the composite separator for a non-aqueous electrolyte secondary battery according to [9] between the positive electrode and the negative electrode.
  • the numerical range represented by using “-” means a range including the numerical values before and after "-" as the lower limit value and the upper limit value.
  • the “non-aqueous electrolytic solution” means an electrolytic solution that does not substantially contain water. That is, the “non-aqueous electrolytic solution” may contain a small amount of water as long as the effect of the present invention is not impaired.
  • the “non-aqueous electrolytic solution” has a water concentration of 200 ppm (mass basis) or less, preferably 100 ppm or less, and more preferably 20 ppm or less.
  • the "non-aqueous electrolyte secondary battery” broadly includes a secondary battery using a non-aqueous electrolyte.
  • the non-aqueous electrolyte secondary battery of the present invention can quickly and more reliably shut down the movement of ions between the positive and negative electrodes when the battery temperature rises, even if the amount of the heat-expandable capsule used is suppressed, and it can be shut down at high temperatures. But this shutdown state can be sustained.
  • the composite separator for a non-aqueous electrolyte secondary battery of the present invention is suitable as a separator for the non-aqueous electrolyte secondary battery of the present invention.
  • the method for manufacturing a non-aqueous electrolyte secondary battery of the present invention even if the amount of the heat-expandable capsule used is suppressed, the exchange of ions between the positive and negative electrodes is quickly and more reliably shut down when the battery temperature rises. It is possible to obtain a non-aqueous electrolyte secondary battery capable of sustaining this shut-down state even at a high temperature.
  • FIG. 1 is an explanatory view (longitudinal sectional view) showing an operating mechanism of a lithium ion secondary battery, which is a form of a non-aqueous electrolyte secondary battery.
  • FIG. 2 is a vertical cross-sectional view showing an example of a specific structure of a non-aqueous electrolyte secondary battery.
  • FIG. 3 is an explanatory view (longitudinal sectional view) schematically showing a state of the composite separator arranged in the non-aqueous electrolytic solution secondary battery of the present invention.
  • FIG. 1 is an explanatory view (longitudinal sectional view) showing an operating mechanism of a lithium ion secondary battery, which is a form of a non-aqueous electrolyte secondary battery.
  • FIG. 2 is a vertical cross-sectional view showing an example of a specific structure of a non-aqueous electrolyte secondary battery.
  • FIG. 3 is an explanatory view (longitudinal sectional view)
  • FIG. 4 is an explanatory view (longitudinal sectional view) schematically showing a state in which the heat-expandable capsule of the composite separator is thermally expanded when the non-aqueous electrolyte secondary battery of the present invention is exposed to a high temperature.
  • FIG. 5 is a vertical cross-sectional view schematically showing the structure of a lamicelle battery, which is a non-aqueous electrolyte secondary battery produced in the examples.
  • the non-aqueous electrolytic solution secondary battery of the present invention has a positive electrode, a negative electrode, and a composite separator arranged between the positive electrode and the negative electrode.
  • This composite separator is a laminate composed of at least two separator sheets, and a heat-expandable capsule is sandwiched between layers of the laminate.
  • the composite separator is a laminate of three or more separator sheets, the laminate has two or more layers.
  • the heat-expandable capsule may be present between any layers. That is, the heat-expandable capsule may be present between one of the two or more layers, or the heat-expandable capsule may be present between the two or more layers.
  • the constituent materials of the plurality of separator sheets constituting one composite separator may be the same or different. From the viewpoint of thinning the obtained non-aqueous electrolytic solution secondary battery, it is preferable that the number of separator sheets constituting the composite separator is two.
  • FIG. 1 is an explanatory diagram (conceptual diagram) showing an operating mechanism of a lithium ion secondary battery, which is a form of a non-aqueous electrolyte secondary battery.
  • the lithium ion secondary battery 10 is capable of inserting and releasing or dissolving and precipitating a non-aqueous electrolyte solution 5, a positive electrode C (positive electrode current collector 1, positive electrode active material layer 2) capable of inserting and releasing lithium ions, and lithium ions.
  • a negative electrode A negative electrode current collector 3, negative electrode active material layer 4) is provided.
  • a separator 9 is arranged between the positive electrode C and the negative electrode A.
  • ⁇ electrons (e ⁇ ) are supplied from the positive electrode side to the negative electrode side via the circuit wiring 7, and lithium ions are emitted from the positive electrode active material layer 2.
  • This lithium ion moves to the negative electrode side through the non-aqueous electrolytic solution 5 and is accumulated in the negative electrode active material layer (a).
  • ⁇ lithium ions accumulated in the negative electrode active material layer are released, and these lithium ions are accumulated in the positive electrode active material layer through the non-aqueous electrolytic solution 5 (b), and at the same time via the circuit wiring 7.
  • Electrons are supplied to the operating mechanism 6. This is the operating mechanism of the lithium-ion secondary battery.
  • the operating mechanism of the non-aqueous electrolyte secondary battery has been conceptually described by taking a lithium ion secondary battery as an example.
  • a specific shape of the non-aqueous electrolyte secondary battery will be described.
  • Specific battery shapes of the non-aqueous electrolyte secondary battery include a bottomed tubular shape, a bottomed square shape, a thin shape, a sheet shape, a paper shape, and the like.
  • the secondary battery may have any shape as long as it functions as a battery by the above-mentioned operating mechanism. Further, it may be a variant such as a horseshoe shape or a comb shape in consideration of the shape of the system or device to be incorporated.
  • FIG. 2 is an example of a bottomed tubular non-aqueous electrolyte secondary battery 100.
  • This battery is a bottomed tubular non-aqueous electrolysis battery in which a positive electrode sheet 14 and a negative electrode sheet 16 stacked via a separator 12 are wound and stored in an outer can 18 (the outer can 18 also serves as a negative electrode current collector). It is a liquid secondary battery 100.
  • 20 in the figure is an insulating plate
  • 22 is a sealing plate
  • 24 is a positive electrode current collector
  • 26 is a gasket
  • 28 is a pressure sensitive valve body
  • 30 is a current blocking element.
  • the hatching is changed in consideration of visibility, but each member corresponds to the overall view by a code.
  • Each material, electrolytic solution, member, etc. used in the non-aqueous electrolytic solution secondary battery of the present invention is not particularly limited except for the structure of the separator. As these materials, members and the like, those used for ordinary non-aqueous electrolyte secondary batteries can be appropriately applied. Further, as for the method for producing the non-aqueous electrolytic solution secondary battery of the present invention, a normal method can be appropriately adopted except for the configuration of the separator. For example, Japanese Patent Application Laid-Open No. 2016-201308, Japanese Patent Application Laid-Open No. 2008-226807, and the like can be appropriately referred to.
  • the composite separator which is a characteristic configuration of the non-aqueous electrolyte secondary battery of the present invention, will be described below.
  • the composite separator used in the non-aqueous electrolyte secondary battery of the present invention is a laminate composed of at least two separator sheets, and a heat-expandable capsule is sandwiched between the layers of the laminate. There is.
  • the composite separator used in the present invention has holes like a normal separator used in a non-aqueous electrolyte secondary battery, and in a normal battery use state, it insulates between the positive and negative electrodes while allowing the electrolytic solution and ions to permeate. Functions as a positive / negative electrode separation membrane.
  • the composite separator of the present invention when the battery temperature rises due to some kind of battery abnormality, a normal separator is thermally melted, and the thermal melting closes the vacancies and blocks the ion conduction between the positive and negative electrodes to function the battery.
  • the heat-expandable capsule When stopped, in the composite separator of the present invention, the heat-expandable capsule rapidly thermally expands prior to the thermal melting of the separator, and the exchange of ions between the positive and negative electrodes is shut down more quickly and more reliably. In addition, this shutdown state can be maintained even under high temperature.
  • the form in which the composite separator used in the present invention has a heat-expandable capsule sandwiched between layers of a laminate composed of two separator sheets will be described below. However, the composite separator used in the present invention is not limited to these forms except as specified in the present invention.
  • FIG. 3 is a vertical cross-sectional view schematically showing one form of a composite separator in a state of being arranged in the non-aqueous electrolyte secondary battery of the present invention.
  • the composite separator 40 has a structure in which two separator sheets 41 and 42 are laminated, and a heat-expandable capsule 43 is sandwiched between layers of the laminated body.
  • the two separator sheets 41 and 42 are usually microporous membranes (microporous membranes) and are in close contact with each other due to the action of the electrolytic solution. That is, in the separator sheet infiltrated with the electrolytic solution, the electrolytic solution acts like an adhesive, and the separator sheets adhere to each other in a laminated state.
  • the composite separator infiltrated with the electrolytic solution is in a state where the two separator sheets 41 and 42 are in close contact with each other by the action of the electrolytic solution in the portion where the heat-expandable capsule 43 is not arranged. is there.
  • the constituent materials of the two separator sheets 41 and 42 may be the same or different.
  • the composite separator 40 arranged in the state shown in FIG. 3 has two separator sheets 41 and 42 along the interface when the battery temperature rises above a predetermined temperature. It expands dimensionally.
  • the state after this thermal expansion is schematically shown in FIG.
  • the composite separator of the non-aqueous electrolyte secondary battery of the present invention creates a state in which there is no electrolyte between the laminated separator sheets when the battery temperature rises for some reason. Stop the battery function.
  • the thermal expansion start temperature (foaming start temperature in the atmosphere (1 atm)) of the heat-expandable capsule is higher than the heat-melting temperature of the separator sheet sandwiching the heat-expandable capsule. It is preferably low, and more preferably 5 ° C. or more lower than the thermal melting temperature of the separator sheet. With such a relationship, it is possible to quickly and more reliably shut down the movement of ions between the positive and negative electrodes when the battery temperature rises.
  • the thermal expansion start temperature of the thermally expandable capsule is usually 70 to 140 ° C., preferably 70 to 120 ° C.
  • the hot melting temperature of the separator sheet is usually 120 to 160 ° C, preferably 120 to 130 ° C.
  • the thermal expansion start temperature of the thermal expansion capsule is a temperature at which the volume of the thermal expansion capsule expands more than twice under 1 atm (1 atm) due to thermal expansion.
  • the hot melting temperature of the separator sheet is synonymous with the melting point of the constituent material of the separator sheet.
  • the melting point of the material having the lowest melting point is defined as the thermal melting temperature of the separator sheet in relation to the thermal expansion start temperature of the heat-expandable capsule.
  • the particle size of the heat-expandable capsule constituting the composite separator is preferably larger than the pore size of the separator sheet sandwiching the heat-expandable capsule, and the heat-expandable capsule of the heat-expandable capsule.
  • the particle size is more preferably 1.5 times or more the pore size of the separator sheet that sandwiches the heat-expandable capsule.
  • the layers of the laminate in which the separator sheets are in close contact with each other are expanded two-dimensionally (in the plane direction) so that the expanding heat-expandable capsule cuts through the layers, and the state where there is no electrolytic solution in the heat generating portion and its surroundings is quickly obtained. Can be created.
  • the non-aqueous electrolytic solution secondary battery usually applies a constant pressure (usually “atmospheric pressure” + “0.05 to 0.1 MPa") in the stacking direction of the composite separator, it is thermally expandable.
  • the capsule does not easily expand in the stacking direction of the separator sheet.
  • the above-mentioned "particle size of the heat-expandable capsule” is the average particle size of the heat-expandable capsule used.
  • the "particle size of the heat-expandable capsule” shall be the volume-based median diameter (d50).
  • the "hole diameter of the separator sheet” 20 holes (entrances of holes) observed on the surface of the separator sheet are randomly observed using an electron microscope, and each of the 20 holes on the surface of the separator sheet is observed. For each, the maximum value of the hole width in the direction perpendicular to the maximum radial direction is measured, and the 20 measured values are arithmetically averaged.
  • the "maximum diameter" of a hole means this distance when the distance from one point on the inner circumference of the hole on the surface of the separator sheet to another point on the inner circumference is maximum.
  • the pore size of the separator sheet is determined in a state where the separator sheet is dried.
  • the particle size of the heat-expandable capsule used in the present invention is preferably 1 to 20 ⁇ m, more preferably 1 to 15 ⁇ m, and even more preferably 1 to 12 ⁇ m. Further, the particle size may be 1 to 10 ⁇ m, may be 1 to 5 ⁇ m, and is preferably 1 to 3 ⁇ m.
  • the pore size of the separator sheet is preferably 1 ⁇ m or less. For example, it can be 0.01 to 1 ⁇ m, may be 0.01 to 0.8 ⁇ m, preferably 0.01 to 0.5 ⁇ m, more preferably 0.02 to 0.2 ⁇ m, and 0.03 to 0. .1 ⁇ m is more preferable.
  • a separator sheet constituting the composite separator a separator usually used in a non-aqueous electrolyte secondary battery can be used without particular limitation as long as the effect of the present invention is not impaired.
  • the constituent material of the separator sheet include a porous polymer material, an inorganic material, an organic-inorganic hybrid material, and glass fiber.
  • the volume ratio occupied by the gaps in the separator sheet, that is, the porosity is preferably 20% to 90%, more preferably 35% to 80%.
  • Examples of the polymer material include cellulose non-woven fabric, polyethylene, polypropylene and the like, and a separator sheet in which these are used in combination can also be used. It is also preferable to laminate two or more kinds of microporous films having different pore diameters, porosities, pore closing temperatures, and the like.
  • Examples of the inorganic material include oxides such as alumina and silicon dioxide; nitrides such as aluminum nitride and silicon nitride; and sulfates such as barium sulfate and calcium sulfate.
  • the heat-expandable capsule is usually formed of a thermoplastic resin containing a foaming agent inside.
  • the foaming agent is not particularly limited as long as it expands at a target temperature.
  • Chemical foaming agents; as well as physical foaming agents such as butane, pentane, hexane, dichloroethane, dichloromethane, freon, air, carbonate gas, nitrogen gas and the like.
  • the thermally expandable capsule used in the present invention is preferably one that expands in volume when the internal pressure becomes sufficient to expand the capsule due to vaporization of the low boiling point liquid inside.
  • a method of controlling the temperature of volume expansion it can be controlled by selecting a liquid whose boiling point is close to a target temperature as the low boiling point liquid to be sealed inside.
  • a known method such as a core selvation method can be adopted for forming the capsule.
  • heat-expandable capsule examples include Expanders 051DU, 007WU, 053WU, 053DU, 054WU, 091DU, 091-080DU, 091-140-DU, 092-120DU, 093-120DU, 820WU, 642WU manufactured by Nippon Ferrite Co., Ltd. , 551WU, 551DU, 551-20WU, 551-20DU, 551-80WU, 551-80DU, 461WU, 461DU, 461-20; Microcapsules F-20, F-30, F-40, manufactured by Matsumoto Oil & Fat Co., Ltd.
  • F-50, F-80S, F-82, F-85, F-100, FN-100 SSD and the like are commercially available. These are composed of an outer shell of a copolymer and a foaming agent composed of a low boiling point hydrocarbon inside the outer shell, and when a predetermined temperature between about 70 ° C. and 200 ° C. is reached, the outer shell portion of the outer shell portion. Due to softening and vaporization of the contents, its own volume expands to, for example, about 40 to 60 times.
  • the thermal expansion start temperature is higher in the electrolytic solution of the non-aqueous electrolytic solution secondary battery (in the electrolytic solution arranged under 1 atm) than the measured value in the atmosphere (1 atm). ) Is preferably 10 ° C. or higher.
  • the thermal expansion response to the rise in battery temperature is enhanced, and it becomes possible to shut down more quickly when a battery abnormality occurs.
  • the thermal expansion start temperature drops in the electrolytic solution of the above-mentioned non-aqueous electrolytic solution secondary battery, the cause is the polarity contained in the electrolytic solution when the thermal expansion microcapsules are immersed in the non-aqueous electrolytic solution. It is conceivable that the solvent will plasticize the capsule wall. The lower the boiling point of the polar solvent contained in the electrolytic solution, the more the decrease in the thermal expansion start temperature tends to become more apparent.
  • the total ratio of the area of the portion where the heat-expandable capsule is arranged (the area of the heat-expandable capsule horizontally projected onto the separator sheet) to the total area of the composite separator is , 50% or less is preferable.
  • this ratio is preferably as small as the range in which the effect of the present invention is exhibited, more preferably 40% or less, further preferably 30% or less, and may be 20% or less.
  • the non-aqueous electrolyte secondary battery of the present invention capable of two-dimensionally controlling the thermal expansion of the heat-expandable capsule can realize a quick shutdown effect. ..
  • the composite separator used in the present invention is preferably in a form in which the separator sheets are adhered to each other around and / or in the vicinity of the composite separator.
  • Adhesion between the separator sheets can be performed by applying heat sealing or the like, and it is preferable to apply heat sealing or the like linearly along the periphery of the composite separator.
  • the composite separator has been described with respect to a state in which it is arranged between the positive electrode and the negative electrode of the non-aqueous electrolyte secondary battery.
  • the above-mentioned composite separator can be independently distributed as a composite separator for a non-aqueous electrolyte secondary battery in a state before being incorporated into the non-aqueous electrolyte secondary battery. That is, according to the present invention, there is provided a composite separator for a non-aqueous electrolyte secondary battery in which a heat-expandable capsule is sandwiched between layers of a laminate composed of at least two separator sheets.
  • the composite separator for a non-aqueous electrolytic solution secondary battery may be in a dry state without being infiltrated with an electrolytic solution or the like, or may be in a wet state by being infiltrated with an electrolytic solution or the like.
  • the size of the composite separator for the non-aqueous electrolyte secondary battery of the present invention is not particularly limited. When a large-sized composite separator is produced and incorporated into a non-aqueous electrolyte secondary battery, it can be cut into a desired size and used.
  • the composite separator of the present invention can be produced by dispersing (sprinkling) heat-expandable capsules substantially uniformly between desired layers when at least two separator sheets are superposed. It is also preferable that after forming a laminate of separator sheets formed by arranging heat-expandable capsules between desired layers, the separator sheets are adhered to each other around and / or in the vicinity thereof. For example, a heat seal having a width of 1 to 10 mm can be applied along the periphery of the composite separator to bond adjacent separator sheets to each other along the periphery of the composite separator.
  • a non-aqueous electrolyte secondary battery can be manufactured using the composite sheet of the present invention. That is, according to the present invention, there is provided a method for manufacturing a non-aqueous electrolyte secondary battery, which comprises arranging the composite separator for the non-aqueous electrolyte secondary battery of the present invention between the positive electrode and the negative electrode. The arrangement of the composite separator for the non-aqueous electrolyte secondary battery between the positive electrode and the negative electrode can be performed in the same manner as the arrangement of the separator in the normal non-aqueous electrolyte secondary battery.
  • the non-aqueous electrolyte secondary battery of the present invention includes, for example, a notebook computer, a pen input computer, a mobile computer, an electronic book player, a mobile phone, a cordless phone slave unit, a pager, a handy terminal, a mobile fax, a mobile copy, a mobile printer, and the like.
  • a non-aqueous electrolytic solution was prepared by dissolving LiPF 6 as a lithium salt at a concentration of 1 M in a non-aqueous solvent containing 40% by mass of ethylene carbonate and 60% by mass of ethyl methyl carbonate.
  • positive electrode active material layer forming material 85% by mass of lithium nickel manganate (LiNi 0.5 Mn 1.5 O 4 ) as the positive electrode active material, 7% by mass of carbon black as the conductive auxiliary agent, and 8% by mass of PVDF (polyvinylidene fluoride) as the binder.
  • the composition to be contained was prepared and used as a positive electrode active material layer forming material.
  • Matsumoto Microsphere-FN-100 SSD manufactured by Matsumoto Yushi Pharmaceutical Co., Ltd., the thermal expansion start temperature is 120 to 130 ° C in the atmosphere (under 1 atm), the average particle size is 6 to 6 to 11 ⁇ m (value published by the manufacturer) was sprinkled substantially uniformly and arranged in a single layer to prepare a composite separator composed of a heat-expandable capsule and two separator sheets sandwiching the same.
  • the ratio of the total area of the portion where the heat-expandable capsules were arranged to the total area of the composite separator was 40 to 48%.
  • the obtained composite separator was used in the non-aqueous electrolyte secondary battery of Example 2. Further, the obtained composite separator was heat-sealed with a width of 5 mm on four sides around the composite separator using a heat sealer, and used in the non-aqueous electrolyte secondary battery of Example 1. Further, two separator sheets were laminated without sandwiching the heat-expandable capsule, and the four sides around the laminate were heat-sealed with a width of 5 mm, which was used for the non-aqueous electrolyte secondary battery of the comparative example. The production of the non-aqueous electrolyte secondary battery will be described below.
  • the laminated cell battery (Lamicelle battery) shown in FIG. 5 was produced as follows (FIG. 5 schematically shows a form in which the composite separator has a heat-expandable capsule).
  • the positive electrode active material layer forming material was applied onto an aluminum current collector foil (length 3.8 cm ⁇ width 5.3 cm ⁇ thickness 80 ⁇ m), dried and pressed to prepare a positive electrode.
  • the negative electrode active material layer forming material was applied onto a copper current collector foil (length 4 cm ⁇ width 5.5 cm ⁇ thickness 80 ⁇ m), dried and pressed to prepare a negative electrode.
  • the battery With the composite separator sandwiched between the positive electrode and the negative electrode, the battery was placed in a bag made of an Al laminated film, an electrolytic solution was injected, and the battery was vacuum-sealed to prepare a lamicelle battery.
  • the obtained lamicelle battery was sandwiched between SUS plates (length 5 cm ⁇ width 7 cm ⁇ thickness 1 mm), restrained at atmospheric pressure + 0.05 MPa, and used in the following test.
  • the shutdown function is exhibited even when the temperature rise is lower by using the composite separator of the present invention. It was also found that by sealing the periphery of the composite separator, the shutdown function begins to appear even in the low temperature range. Further, even if the hot melting state of the separator sheet progresses due to a high temperature (180 ° C. or higher) and the separator sheet itself cannot maintain a high shutdown state, the above-mentioned high temperature state can be obtained by using the composite separator of the present invention. So, I also found that the shutdown state can be further enhanced.

Abstract

A nonaqueous electrolyte secondary battery which comprises a positive electrode, a negative electrode and a composite separator that is arranged between the positive electrode and the negative electrode, wherein the composite separator is obtained by sandwiching thermally expandable capsules between layers of a multilayer body that is composed of at least two separator sheets; a composite separator which is suitable for this nonaqueous electrolyte secondary battery; and a method for producing this nonaqueous electrolyte secondary battery.

Description

非水電解液二次電池、これに用いるセパレータ、及び非水電解液二次電池の製造方法Non-aqueous electrolyte secondary battery, separator used for this, and method for manufacturing non-aqueous electrolyte secondary battery
　本発明は、非水電解液二次電池、これに用いるセパレータ、及び非水電解液二次電池の製造方法に関する。 The present invention relates to a non-aqueous electrolyte secondary battery, a separator used for the non-aqueous electrolyte secondary battery, and a method for manufacturing the non-aqueous electrolyte secondary battery.
　リチウムイオン二次電池に代表される非水電解液二次電池は、高エネルギー密度であり、貯蔵性能、低温動作性等にも優れ、携帯電話、ノートパソコン等のポータブル電子機器に広く利用されている。また、電池を大型化して、自動車をはじめとした輸送機器にも使用されるようになり、また夜間電力、自然エネルギー発電による電力等の貯蔵装置としての利用も進められている。 Non-aqueous electrolyte secondary batteries represented by lithium-ion secondary batteries have high energy density, excellent storage performance, low-temperature operability, etc., and are widely used in portable electronic devices such as mobile phones and laptop computers. There is. In addition, the size of batteries has been increased so that they can be used in transportation equipment such as automobiles, and they are also being used as storage devices for nighttime electric power and electric power generated by natural energy power generation.
　非水電解液二次電池は、電極中に含まれる不純物金属などが原因で内部短絡が生じると、電池の温度が局所的に上昇する。この局所的な温度上昇は、いわゆる熱暴走の引き金となる。
　この熱暴走に対処する技術として、特許文献１には、リチウムイオン電池において、正極と負極との間に配される電解液に浸潤されたセパレータに、熱膨張（性）カプセルを添加することが記載されている。特許文献１記載の技術によれば、電池温度上昇時に熱膨張性カプセルが膨張し、電極間に配されたセパレータ内で電解液のない空間が形成されてリチウムイオンの移動を物理的にシャットアウトし、熱暴走を抑制できるとされる。
　また、特許文献２には、正極活物質層、電解質層、及び負極活物質層の少なくとも１層の表面又は内部にガス発生剤を含み、二次電池の温度が６０℃以上３００℃未満に達したときに、ガス発生剤からガスが発生することを特徴とする非水電解質二次電池が記載され、１Ｈ－テトラゾール（ガス発生剤）を２枚のセパレータで挟持したものをセパレータの代わりに用いた電池形態も開示されている。特許文献２記載の技術によれば、非水電解質二次電池の温度が上昇した際にガス発生剤からガスが発生して拡散する。この拡散ガスが正極活物質層、セパレータ、負極活物質層などの空孔に入り込み、正極活物質層と負極活物質層との間を行き来するイオンの移動経路を狭めたり、遮断したりして内部抵抗を増大させて、さらなる温度上昇、過電流等の発生を抑えることができるとされる。 In a non-aqueous electrolyte secondary battery, when an internal short circuit occurs due to an impurity metal contained in an electrode or the like, the temperature of the battery rises locally. This local temperature rise triggers so-called thermal runaway.
As a technique for dealing with this thermal runaway, Patent Document 1 states that in a lithium ion battery, a thermal expansion (sex) capsule is added to a separator infiltrated with an electrolytic solution arranged between a positive electrode and a negative electrode. Are listed. According to the technique described in Patent Document 1, the thermally expandable capsule expands when the battery temperature rises, and a space without an electrolytic solution is formed in the separator arranged between the electrodes to physically shut out the movement of lithium ions. However, it is said that thermal runaway can be suppressed.
Further, Patent Document 2 contains a gas generating agent on the surface or inside of at least one of the positive electrode active material layer, the electrolyte layer, and the negative electrode active material layer, and the temperature of the secondary battery reaches 60 ° C. or higher and lower than 300 ° C. A non-aqueous electrolyte secondary battery characterized in that gas is generated from the gas generating agent is described, and a 1H-tetrazole (gas generating agent) sandwiched between two separators is used instead of the separator. The battery form that was used is also disclosed. According to the technique described in Patent Document 2, when the temperature of the non-aqueous electrolyte secondary battery rises, gas is generated from the gas generating agent and diffused. This diffused gas enters the pores of the positive electrode active material layer, separator, negative electrode active material layer, etc., and narrows or blocks the movement path of ions that travel between the positive electrode active material layer and the negative electrode active material layer. It is said that the internal resistance can be increased to suppress further temperature rise, overcurrent, and the like.
特開２００９－２６６７４号公報Japanese Unexamined Patent Publication No. 2009-266774 特開２００８－２２６８０７号公報Japanese Unexamined Patent Publication No. 2008-226807
　上記各特許文献に記載された熱膨張性カプセル及びガス発生剤は異物であり、通常時の電池性能の向上においては不利に働く。そのため、これらの使用量は極力抑えることが要求される。
　しかし、特許文献１記載の方法では、熱膨張性カプセルの熱膨張方向を制御することができず、熱膨張性カプセルの使用量の低減と、シャットダウン機能の向上（シャットダウン機能の高速化、効率化等）との両立には制約がある。
　また、特許文献２記載の技術では、ガス発生剤から生じたガスは電池内に制限なく拡散するため、シャットダウンには多量のガスが必要となり、シャットダウンの高速化にも制約がある。
　さらに、特許文献１及び２のいずれの方法でも、電池が高温状態となりセパレータ自体の熱溶融が進行した場合には、形成されたシャットダウン状態を安定に維持することは難しい。
　本発明は、熱膨張性カプセルの使用量を抑えても、電池温度上昇時に正負極間のイオンの行き来を、素早く、より確実にシャットダウンすることができ、高温下でもこのシャットダウン状態を持続することができる非水電解液二次電池、この非水電解液二次電池に好適な複合セパレータ、及びこの非水電解液二次電池の製造方法を提供することを課題とする。 The heat-expandable capsules and gas generating agents described in the above patent documents are foreign substances and work disadvantageously in improving the battery performance in normal times. Therefore, it is required to reduce the amount of these used as much as possible.
However, the method described in Patent Document 1 cannot control the thermal expansion direction of the heat-expandable capsule, and reduces the amount of the heat-expandable capsule used and improves the shutdown function (speeding up and improving the efficiency of the shutdown function). Etc.), there are restrictions on compatibility.
Further, in the technique described in Patent Document 2, since the gas generated from the gas generating agent diffuses into the battery without limitation, a large amount of gas is required for shutdown, and there is a limitation in speeding up the shutdown.
Further, in any of the methods of Patent Documents 1 and 2, it is difficult to stably maintain the formed shutdown state when the battery becomes a high temperature state and the separator itself is thermally melted.
According to the present invention, even if the amount of the heat-expandable capsule used is suppressed, the movement of ions between the positive and negative electrodes can be quickly and more reliably shut down when the battery temperature rises, and this shut-down state can be maintained even at high temperatures. It is an object of the present invention to provide a non-aqueous electrolyte secondary battery capable of producing a non-aqueous electrolyte secondary battery, a composite separator suitable for the non-aqueous electrolyte secondary battery, and a method for producing the non-aqueous electrolyte secondary battery.
　本発明者らは上記課題に鑑み鋭意検討を重ねた。その結果、非水電解液二次電池において、正極活物質層と負極活物質層との間に配するセパレータとして、電解液の作用で互いに密着した２枚のセパレータの間に熱膨張性カプセルを挟持したものを採用することにより、電池温度上昇時には２枚のセパレータ間に沿って、二次元的（平面的）に、熱膨張性カプセルが素早く膨張してシャットダウンできること、このシャットダウン状態を、セパレータ自身の熱溶融が進行しても十分に維持できることを見い出した。さらに、上記の熱膨張性カプセルの膨張方向は二次元的に制御されるために、電池性能の向上には不利な異物である熱膨張性カプセルを少量としても、上記の効果が得られることも明らかとなってきた。
　本発明はこれらの知見に基づきさらに検討を重ねて完成されるに至ったものである。 The present inventors have made extensive studies in view of the above problems. As a result, in the non-aqueous electrolyte secondary battery, as a separator to be arranged between the positive electrode active material layer and the negative electrode active material layer, a heat-expandable capsule is placed between two separators that are in close contact with each other by the action of the electrolytic solution. By adopting the sandwiched one, the heat-expandable capsule can be quickly expanded and shut down in a two-dimensional (planar) manner along the space between the two separators when the battery temperature rises. It was found that even if the thermal melting of the above progresses, it can be sufficiently maintained. Further, since the expansion direction of the heat-expandable capsule is controlled two-dimensionally, the above-mentioned effect can be obtained even if the amount of the heat-expandable capsule, which is a foreign substance disadvantageous for improving the battery performance, is small. It has become clear.
Based on these findings, the present invention has been further studied and completed.
　上記の課題は以下の手段により解決された。
〔１〕
　正極と、負極と、正極と負極との間に配された複合セパレータとを有する非水電解液二次電池であって、
　上記複合セパレータは、少なくとも２枚のセパレータシートで構成された積層体の層間に熱膨張性カプセルを挟持してなる、非水電解液二次電池。
〔２〕
　上記非水電解液二次電池中において、上記熱膨張性カプセルの熱膨張開始温度が、熱膨張性カプセルを挟持する上記セパレータシートの熱溶融温度よりも５℃以上低い、〔１〕に記載の非水電解液二次電池。
〔３〕
　上記熱膨張性カプセルの粒径が、熱膨張性カプセルを挟持する上記セパレータシートの孔径の１．５倍以上である、〔１〕又は〔２〕に記載の非水電解液二次電池。
〔４〕
　上記熱膨張性カプセルの熱膨張開始温度が、大気中における測定値よりも、上記電解液中における測定値が１０℃以上低い、〔１〕～〔３〕のいずれかに記載の非水電解液二次電池。
〔５〕
　上記複合セパレータは、平面視において、複合セパレータ全体の面積に占める、熱膨張性カプセルが配された部分の面積の合計の割合が、５０％以下である、〔１〕～〔４〕のいずれかに記載の非水電解液二次電池。
〔６〕
　上記非水電解液二次電池において、上記複合セパレータは、セパレータシートの積層方向に加圧された状態にある、〔１〕～〔５〕のいずれかに記載の非水電解液二次電池。
〔７〕
　上記非水電解液二次電池において、上記複合セパレータを構成するセパレータシートが微多孔膜であり、上記複合セパレータを構成するセパレータシート同士が電解液の作用により密着している、〔１〕～〔６〕のいずれかに記載の非水電解液二次電池。
〔８〕
　上記複合セパレータの周囲及び／又はその近傍において、セパレータシート同士が接着されている、〔１〕～〔７〕のいずれかに記載の非水電解液二次電池。
〔９〕
　少なくとも２枚のセパレータシートで構成された積層体の層間に熱膨張性カプセルを挟持してなる、非水電解液二次電池用複合セパレータ。
〔１０〕
　〔９〕に記載の非水電解液二次電池用複合セパレータを正極と負極との間に配することを含む、非水電解液二次電池の製造方法。 The above problems have been solved by the following means.
[1]
A non-aqueous electrolyte secondary battery having a positive electrode, a negative electrode, and a composite separator arranged between the positive electrode and the negative electrode.
The composite separator is a non-aqueous electrolyte secondary battery in which a heat-expandable capsule is sandwiched between layers of a laminate composed of at least two separator sheets.
[2]
The thermal expansion start temperature of the thermal expansion capsule in the non-aqueous electrolyte secondary battery is 5 ° C. or more lower than the thermal melting temperature of the separator sheet sandwiching the thermal expansion capsule, according to [1]. Non-aqueous electrolyte secondary battery.
[3]
The non-aqueous electrolyte secondary battery according to [1] or [2], wherein the particle size of the heat-expandable capsule is 1.5 times or more the pore size of the separator sheet sandwiching the heat-expandable capsule.
[4]
The non-aqueous electrolytic solution according to any one of [1] to [3], wherein the thermal expansion start temperature of the thermally expandable capsule is lower than the measured value in the atmosphere by 10 ° C. or more in the electrolytic solution. Secondary battery.
[5]
The composite separator is any one of [1] to [4], wherein the ratio of the total area of the portion where the heat-expandable capsule is arranged to the total area of the composite separator is 50% or less in a plan view. The non-aqueous electrolyte secondary battery described in.
[6]
The non-aqueous electrolyte secondary battery according to any one of [1] to [5], wherein the composite separator is in a state of being pressurized in the stacking direction of the separator sheets in the non-aqueous electrolyte secondary battery.
[7]
In the non-aqueous electrolytic solution secondary battery, the separator sheet constituting the composite separator is a microporous film, and the separator sheets constituting the composite separator are in close contact with each other by the action of the electrolytic solution. 6] The non-aqueous electrolyte secondary battery according to any one of.
[8]
The non-aqueous electrolyte secondary battery according to any one of [1] to [7], wherein the separator sheets are adhered to each other around and / or in the vicinity of the composite separator.
[9]
A composite separator for a non-aqueous electrolyte secondary battery, in which a heat-expandable capsule is sandwiched between layers of a laminate composed of at least two separator sheets.
[10]
A method for producing a non-aqueous electrolyte secondary battery, which comprises arranging the composite separator for a non-aqueous electrolyte secondary battery according to [9] between the positive electrode and the negative electrode.
　本発明の説明において、「～」を用いて表される数値範囲は、「～」の前後に記載される数値を下限値及び上限値として含む範囲を意味する。
　本発明において「非水電解液」とは、水を実質的に含まない電解液を意味する。すなわち、「非水電解液」は本発明の効果を妨げない範囲で微量の水を含んでいてもよい。本発明において「非水電解液」は、水の濃度が２００ｐｐｍ（質量基準）以下であり、１００ｐｐｍ以下が好ましく２０ｐｐｍ以下がより好ましい。なお、非水電解液を完全に無水とすることは現実的に困難であり、通常は水が１ｐｐｍ以上含まれる。
　本発明において「非水電解液二次電池」には、非水電解液を用いた二次電池が広く包含される。 In the description of the present invention, the numerical range represented by using "-" means a range including the numerical values before and after "-" as the lower limit value and the upper limit value.
In the present invention, the "non-aqueous electrolytic solution" means an electrolytic solution that does not substantially contain water. That is, the "non-aqueous electrolytic solution" may contain a small amount of water as long as the effect of the present invention is not impaired. In the present invention, the "non-aqueous electrolytic solution" has a water concentration of 200 ppm (mass basis) or less, preferably 100 ppm or less, and more preferably 20 ppm or less. It is practically difficult to make the non-aqueous electrolytic solution completely anhydrous, and usually contains 1 ppm or more of water.
In the present invention, the "non-aqueous electrolyte secondary battery" broadly includes a secondary battery using a non-aqueous electrolyte.
　本発明の非水電解液二次電池は、熱膨張性カプセルの使用量を抑えても、電池温度上昇時に正負極間のイオンの行き来を、素早く、より確実にシャットダウンすることができ、高温下でもこのシャットダウン状態を持続することができる。また、本発明の非水電解液二次電池用複合セパレータは、本発明の非水電解液二次電池のセパレータとして好適である。また、本発明の非水電解液二次電池の製造方法によれば、熱膨張性カプセルの使用量を抑えても、電池温度上昇時に正負極間のイオンの行き来を素早く、より確実にシャットダウンすることができ、高温下でもこのシャットダウン状態を持続することができる非水電解液二次電池を得ることができる。 The non-aqueous electrolyte secondary battery of the present invention can quickly and more reliably shut down the movement of ions between the positive and negative electrodes when the battery temperature rises, even if the amount of the heat-expandable capsule used is suppressed, and it can be shut down at high temperatures. But this shutdown state can be sustained. Further, the composite separator for a non-aqueous electrolyte secondary battery of the present invention is suitable as a separator for the non-aqueous electrolyte secondary battery of the present invention. Further, according to the method for manufacturing a non-aqueous electrolyte secondary battery of the present invention, even if the amount of the heat-expandable capsule used is suppressed, the exchange of ions between the positive and negative electrodes is quickly and more reliably shut down when the battery temperature rises. It is possible to obtain a non-aqueous electrolyte secondary battery capable of sustaining this shut-down state even at a high temperature.
図１は、非水電解液二次電池の一形態であるリチウムイオン二次電池の作動機構を示す説明図（縦断面図）である。FIG. 1 is an explanatory view (longitudinal sectional view) showing an operating mechanism of a lithium ion secondary battery, which is a form of a non-aqueous electrolyte secondary battery. 図２は、非水電解液二次電池の具体的構造の一例を示す縦断面図である。FIG. 2 is a vertical cross-sectional view showing an example of a specific structure of a non-aqueous electrolyte secondary battery. 図３は、本発明の非水電解液二次電池に配された複合セパレータの状態を模式的に示す説明図（縦断面図）である。FIG. 3 is an explanatory view (longitudinal sectional view) schematically showing a state of the composite separator arranged in the non-aqueous electrolytic solution secondary battery of the present invention. 図４は、本発明の非水電解液二次電池が高温に曝されたとき、複合セパレータの熱膨張性カプセルが熱膨張した状態を模式的に示す説明図（縦断面図）である。FIG. 4 is an explanatory view (longitudinal sectional view) schematically showing a state in which the heat-expandable capsule of the composite separator is thermally expanded when the non-aqueous electrolyte secondary battery of the present invention is exposed to a high temperature. 図５は、実施例で作製した非水電解液二次電池であるラミセル電池の構造を模式的に示す縦断面図である。FIG. 5 is a vertical cross-sectional view schematically showing the structure of a lamicelle battery, which is a non-aqueous electrolyte secondary battery produced in the examples.
　本発明の非水電解液二次電池の好ましい実施形態を説明するが、本発明は、本発明で規定すること以外は、これらの形態に限定されるものではない。 A preferred embodiment of the non-aqueous electrolyte secondary battery of the present invention will be described, but the present invention is not limited to these embodiments except as specified in the present invention.
［非水電解液二次電池］
　本発明の非水電解液二次電池は、正極と、負極と、正極と負極との間に配された複合セパレータとを有する。この複合セパレータは、少なくとも２枚のセパレータシートで構成された積層体であり、この積層体の層間には熱膨張性カプセルが挟持されている。
　複合セパレータが３枚以上のセパレータシートの積層体の場合、この積層体は層間を２つ以上有する。この場合、熱膨張性カプセルはいずれの層間に存在していてもよい。すなわち、２つ以上の層間のうち１つの層間に熱膨張性カプセルが存在する形態でもよく、２つ以上の層間に熱膨張性カプセルが存在していてもよい。
　１つの複合セパレータを構成する複数のセパレータシートの構成材料は、同一でもよく、異なってもよい。
　得られる非水電解液二次電池の薄膜化の観点から、複合セパレータを構成するセパレータシートは２枚であることが好ましい。 [Non-aqueous electrolyte secondary battery]
The non-aqueous electrolytic solution secondary battery of the present invention has a positive electrode, a negative electrode, and a composite separator arranged between the positive electrode and the negative electrode. This composite separator is a laminate composed of at least two separator sheets, and a heat-expandable capsule is sandwiched between layers of the laminate.
When the composite separator is a laminate of three or more separator sheets, the laminate has two or more layers. In this case, the heat-expandable capsule may be present between any layers. That is, the heat-expandable capsule may be present between one of the two or more layers, or the heat-expandable capsule may be present between the two or more layers.
The constituent materials of the plurality of separator sheets constituting one composite separator may be the same or different.
From the viewpoint of thinning the obtained non-aqueous electrolytic solution secondary battery, it is preferable that the number of separator sheets constituting the composite separator is two.
　本発明の非水電解液二次電池は、セパレータの構成以外は、通常の非水電解液二次電池の構成を採用することができる。
　図１は、非水電解液二次電池の一形態であるリチウムイオン二次電池の作動機構を示す説明図（概念図）である。リチウムイオン二次電池１０は、非水電解液５と、リチウムイオンの挿入放出が可能な正極Ｃ（正極集電体１、正極活物質層２）と、リチウムイオンの挿入放出または溶解析出が可能な負極Ａ（負極集電体３，負極活物質層４）とを備える。正極Ｃと負極Ａの間にはセパレータ９が配される。このような電池構成とすることにより、充電（α）時には正極側から負極側へと回路配線７を介して電子（ｅ－）が供給され、正極活物質層２からはリチウムイオンが放出されて、このリチウムイオンは非水電解液５を通じて負極側へと移動し、負極活物質層へと蓄積される（ａ）。また、放電（β）時には負極活物質層に蓄積されたリチウムイオンが放出されて、このリチウムイオンは非水電解液５を通じて正極活物質層へと蓄積され（ｂ）、同時に回路配線７を介して動作機構６に電子が供給される。これが、リチウムイオン二次電池の作動機構である。 As the non-aqueous electrolyte secondary battery of the present invention, the configuration of a normal non-aqueous electrolyte secondary battery can be adopted except for the configuration of the separator.
FIG. 1 is an explanatory diagram (conceptual diagram) showing an operating mechanism of a lithium ion secondary battery, which is a form of a non-aqueous electrolyte secondary battery. The lithium ion secondary battery 10 is capable of inserting and releasing or dissolving and precipitating a non-aqueous electrolyte solution 5, a positive electrode C (positive electrode current collector 1, positive electrode active material layer 2) capable of inserting and releasing lithium ions, and lithium ions. A negative electrode A (negative electrode current collector 3, negative electrode active material layer 4) is provided. A separator 9 is arranged between the positive electrode C and the negative electrode A. With such a battery configuration, during charging (α), electrons (e − ) are supplied from the positive electrode side to the negative electrode side via the circuit wiring 7, and lithium ions are emitted from the positive electrode active material layer 2. , This lithium ion moves to the negative electrode side through the non-aqueous electrolytic solution 5 and is accumulated in the negative electrode active material layer (a). Further, at the time of discharge (β), lithium ions accumulated in the negative electrode active material layer are released, and these lithium ions are accumulated in the positive electrode active material layer through the non-aqueous electrolytic solution 5 (b), and at the same time via the circuit wiring 7. Electrons are supplied to the operating mechanism 6. This is the operating mechanism of the lithium-ion secondary battery.
　上記ではリチウムイオン二次電池を例として非水電解液二次電池の作動機構を概念的に説明した。続いて非水電解液二次電池の具体的な形状について説明する。非水電解液二次電池の具体的な電池形状としては、有底筒型形状、有底角型形状、薄型形状、シート形状およびペーパー形状などが知られており、本発明の非水電解液二次電池は、上記作動機構により電池として機能すれば、いずれの形状であってもよい。また、組み込まれるシステム、機器等の形を考慮した馬蹄形や櫛型形状等の異型のものであってもよい。
　図２は、有底筒型非水電解液二次電池１００の一例である。この電池は、セパレータ１２を介して重ね合わせた正極シート１４、負極シート１６を巻回して外装缶１８（この外装缶１８は負極集電体を兼ねる）内に収納した有底筒型非水電解液二次電池１００となっている。その他、図中の２０が絶縁板、２２が封口板、２４が正極集電体、２６がガスケット、２８が圧力感応弁体、３０が電流遮断素子である。なお、拡大した円内の図示は視認性を考慮しハッチングを変えているが、各部材は符号により全体図と対応している。 In the above, the operating mechanism of the non-aqueous electrolyte secondary battery has been conceptually described by taking a lithium ion secondary battery as an example. Next, a specific shape of the non-aqueous electrolyte secondary battery will be described. Specific battery shapes of the non-aqueous electrolyte secondary battery include a bottomed tubular shape, a bottomed square shape, a thin shape, a sheet shape, a paper shape, and the like. The secondary battery may have any shape as long as it functions as a battery by the above-mentioned operating mechanism. Further, it may be a variant such as a horseshoe shape or a comb shape in consideration of the shape of the system or device to be incorporated.
FIG. 2 is an example of a bottomed tubular non-aqueous electrolyte secondary battery 100. This battery is a bottomed tubular non-aqueous electrolysis battery in which a positive electrode sheet 14 and a negative electrode sheet 16 stacked via a separator 12 are wound and stored in an outer can 18 (the outer can 18 also serves as a negative electrode current collector). It is a liquid secondary battery 100. In addition, 20 in the figure is an insulating plate, 22 is a sealing plate, 24 is a positive electrode current collector, 26 is a gasket, 28 is a pressure sensitive valve body, and 30 is a current blocking element. In the enlarged circle, the hatching is changed in consideration of visibility, but each member corresponds to the overall view by a code.
　本発明の非水電解液二次電池に用いる各材料、電解液、部材等は、セパレータの構成を除いて特に制限されない。これらの材料、部材等は、通常の非水電解液二次電池に用いられるものを適宜に適用することができる。また、本発明の非水電解液二次電池の作製方法についても、セパレータの構成を除いては、通常の方法を適宜に採用することができる。例えば、特開２０１６－２０１３０８号公報、特開２００８－２２６８０７号公報等を適宜に参照することができる。
　本発明の非水電解液二次電池の特徴的な構成である複合セパレータについて以下に説明する。 Each material, electrolytic solution, member, etc. used in the non-aqueous electrolytic solution secondary battery of the present invention is not particularly limited except for the structure of the separator. As these materials, members and the like, those used for ordinary non-aqueous electrolyte secondary batteries can be appropriately applied. Further, as for the method for producing the non-aqueous electrolytic solution secondary battery of the present invention, a normal method can be appropriately adopted except for the configuration of the separator. For example, Japanese Patent Application Laid-Open No. 2016-201308, Japanese Patent Application Laid-Open No. 2008-226807, and the like can be appropriately referred to.
The composite separator, which is a characteristic configuration of the non-aqueous electrolyte secondary battery of the present invention, will be described below.
＜複合セパレータ＞
　本発明の非水電解液二次電池に用いる複合セパレータは、上記の通り、少なくとも２枚のセパレータシートで構成された積層体であり、この積層体の層間には熱膨張性カプセルが挟持されている。本発明に用いる複合セパレータは、非水電解液二次電池に用いる通常のセパレータと同様、空孔を有し、通常の電池の使用状態では電解液及びイオンを透過しながら正負極間を絶縁する正負極分離膜として機能する。また、何らかの電池異常が生じて電池温度が上昇した際には、通常のセパレータであれば熱溶融し、この熱溶融により空孔を閉塞して正負極間のイオン伝導を遮断して電池機能を停止するところ、本発明の複合セパレータは、セパレータの熱溶融に先んじて熱膨張性カプセルが素早く熱膨張し、正負極間のイオンの行き来を、素早く、より確実にシャットダウンする。また、高温下でもこのシャットダウン状態を持続することができる。
　本発明に用いる複合セパレータが、２枚のセパレータシートからなる積層体の層間に熱膨張性カプセルを挟持した形態について以下に説明する。ただし、本発明に用いる複合セパレータは、本発明で規定すること以外はこれらの形態に限定されるものではない。 <Composite separator>
As described above, the composite separator used in the non-aqueous electrolyte secondary battery of the present invention is a laminate composed of at least two separator sheets, and a heat-expandable capsule is sandwiched between the layers of the laminate. There is. The composite separator used in the present invention has holes like a normal separator used in a non-aqueous electrolyte secondary battery, and in a normal battery use state, it insulates between the positive and negative electrodes while allowing the electrolytic solution and ions to permeate. Functions as a positive / negative electrode separation membrane. In addition, when the battery temperature rises due to some kind of battery abnormality, a normal separator is thermally melted, and the thermal melting closes the vacancies and blocks the ion conduction between the positive and negative electrodes to function the battery. When stopped, in the composite separator of the present invention, the heat-expandable capsule rapidly thermally expands prior to the thermal melting of the separator, and the exchange of ions between the positive and negative electrodes is shut down more quickly and more reliably. In addition, this shutdown state can be maintained even under high temperature.
The form in which the composite separator used in the present invention has a heat-expandable capsule sandwiched between layers of a laminate composed of two separator sheets will be described below. However, the composite separator used in the present invention is not limited to these forms except as specified in the present invention.
　図３は、本発明の非水電解液二次電池に配された状態の複合セパレータの一形態を模式的に示す縦断面図である。図３に示すように、複合セパレータ４０は、２枚のセパレータシート４１、４２が積層された構成を有し、この積層体の層間には熱膨張性カプセル４３が挟持されている。２枚のセパレータシート４１、４２は、通常は微多孔質の膜（微多孔膜）であり、電解液の作用で密着している。すなわち、電解液に浸潤したセパレータシートは、電解液が接着剤のように作用して、積層状態でセパレータシート同士が密着する。これは、たとえるなら、ティッシュペーパーに水を吸わせると密着性が高まる現象と同じである。したがって、非水電解液二次電池において、電解液に浸潤した複合セパレータは、熱膨張性カプセル４３が配されていない部分において２枚のセパレータシート４１、４２が電解液の作用で密着した状態にある。なお、２枚のセパレータシート４１、４２の構成材料は同一でもよく、異なってもよい。 FIG. 3 is a vertical cross-sectional view schematically showing one form of a composite separator in a state of being arranged in the non-aqueous electrolyte secondary battery of the present invention. As shown in FIG. 3, the composite separator 40 has a structure in which two separator sheets 41 and 42 are laminated, and a heat-expandable capsule 43 is sandwiched between layers of the laminated body. The two separator sheets 41 and 42 are usually microporous membranes (microporous membranes) and are in close contact with each other due to the action of the electrolytic solution. That is, in the separator sheet infiltrated with the electrolytic solution, the electrolytic solution acts like an adhesive, and the separator sheets adhere to each other in a laminated state. This is, for example, the same phenomenon that the adhesion increases when the tissue paper is made to absorb water. Therefore, in the non-aqueous electrolytic solution secondary battery, the composite separator infiltrated with the electrolytic solution is in a state where the two separator sheets 41 and 42 are in close contact with each other by the action of the electrolytic solution in the portion where the heat-expandable capsule 43 is not arranged. is there. The constituent materials of the two separator sheets 41 and 42 may be the same or different.
　本発明の非水電解液二次電池において図３に示す状態で配された複合セパレータ４０は、電池温度が所定温度以上にまで上昇すると、２枚のセパレータシート４１、４２の界面に沿って二次元的に膨張する。この熱膨張後の状態を図４に模式的に示す。図４に示すように、本発明の非水電解液二次電池が有する複合セパレータは、何らかの原因で電池温度が上昇した際に、積層されたセパレータシートの間に電解液のない状態を作り出し、電池機能を停止する。 In the non-aqueous electrolyte secondary battery of the present invention, the composite separator 40 arranged in the state shown in FIG. 3 has two separator sheets 41 and 42 along the interface when the battery temperature rises above a predetermined temperature. It expands dimensionally. The state after this thermal expansion is schematically shown in FIG. As shown in FIG. 4, the composite separator of the non-aqueous electrolyte secondary battery of the present invention creates a state in which there is no electrolyte between the laminated separator sheets when the battery temperature rises for some reason. Stop the battery function.
　本発明の非水電解液二次電池において、熱膨張性カプセルの熱膨張開始温度（大気中（１気圧）における発泡開始温度）は、熱膨張性カプセルを挟持するセパレータシートの熱溶融温度よりも低いことが好ましく、セパレータシートの熱溶融温度よりも５℃以上低いことがより好ましい。このような関係とすることにより、電池温度上昇時に正負極間のイオンの行き来を、素早く、より確実にシャットダウンすることができる。熱膨張性カプセルの上記熱膨張開始温度は、通常は７０～１４０℃であり、７０～１２０℃が好ましい。また、セパレータシートの熱溶融温度は通常は１２０～１６０℃であり、１２０～１３０℃が好ましい。
　ここで、熱膨張性カプセルの熱膨張開始温度とは、熱膨張により熱膨張性カプセルの体積が、１気圧（１ａｔｍ）下で、２倍以上に膨張する温度である。また、セパレータシートの熱溶融温度とは、セパレータシートの構成材料の融点と同義である。セパレータシートの構成材料が２種以上の場合、上記の熱膨張性カプセルの熱膨張開始温度との関係については、最も融点の低い材料の融点を、セパレータシートの熱溶融温度とする。 In the non-aqueous electrolyte secondary battery of the present invention, the thermal expansion start temperature (foaming start temperature in the atmosphere (1 atm)) of the heat-expandable capsule is higher than the heat-melting temperature of the separator sheet sandwiching the heat-expandable capsule. It is preferably low, and more preferably 5 ° C. or more lower than the thermal melting temperature of the separator sheet. With such a relationship, it is possible to quickly and more reliably shut down the movement of ions between the positive and negative electrodes when the battery temperature rises. The thermal expansion start temperature of the thermally expandable capsule is usually 70 to 140 ° C., preferably 70 to 120 ° C. The hot melting temperature of the separator sheet is usually 120 to 160 ° C, preferably 120 to 130 ° C.
Here, the thermal expansion start temperature of the thermal expansion capsule is a temperature at which the volume of the thermal expansion capsule expands more than twice under 1 atm (1 atm) due to thermal expansion. Further, the hot melting temperature of the separator sheet is synonymous with the melting point of the constituent material of the separator sheet. When two or more kinds of constituent materials of the separator sheet are used, the melting point of the material having the lowest melting point is defined as the thermal melting temperature of the separator sheet in relation to the thermal expansion start temperature of the heat-expandable capsule.
　本発明の非水電解液二次電池において、複合セパレータを構成する熱膨張性カプセルの粒径は、この熱膨張性カプセルを挟持するセパレータシートの孔径よりも大きいことが好ましく、熱膨張性カプセルの粒径は熱膨張性カプセルを挟持するセパレータシートの孔径の１．５倍以上であることがより好ましい。このような関係とすることにより、熱膨張性カプセルがセパレータシート内に入り込みにくく、熱膨張性カプセルが熱膨張した際に、その膨張方向を、積層されたセパレータシート同士の界面に沿った方向へとより確実に制御できる。つまり、セパレータシート同士が密着した積層体の層間を、膨張する熱膨張性カプセルが層間を切り開くように二次元的（平面方向）に膨張し、発熱部位とその周辺に電解液がない状態を素早く作り出すことができる。なお、非水電解液二次電池は、複合セパレータの積層方向には通常、一定の圧（通常は「大気圧」＋「０．０５～０．１ＭＰａ」）がかかっているため、熱膨張性カプセルはセパレータシートの積層方向には膨張しにくい。
　上記の「熱膨張性カプセルの粒径」は、使用する熱膨張性カプセルの平均粒子径である。この平均粒子径は、熱膨張性カプセルの製造メーカーないし販売メーカーが公表している。メーカー公表の平均粒子径が不明の場合には、「熱膨張性カプセルの粒径」は体積基準のメディアン径（ｄ５０）とする。
　また、「セパレータシートの孔径」は、セパレータシートを、電子顕微鏡を用いてその表面に観察される２０個の孔（孔の入口）を無作為に観察し、セパレータシート表面における２０個の各孔それぞれについて、最大径方向に対して垂直方向の孔の幅の最大値を測定し、２０個の測定値を算術平均した値とする。孔の「最大径」とは、セパレータシート表面における孔の内周のある一点から、この内周の他の点までの距離が最大となるとき、この距離を意味する。セパレータシートの孔径は、セパレータシートを乾燥させた状態で行う。 In the non-aqueous electrolyte secondary battery of the present invention, the particle size of the heat-expandable capsule constituting the composite separator is preferably larger than the pore size of the separator sheet sandwiching the heat-expandable capsule, and the heat-expandable capsule of the heat-expandable capsule. The particle size is more preferably 1.5 times or more the pore size of the separator sheet that sandwiches the heat-expandable capsule. With such a relationship, it is difficult for the heat-expandable capsule to enter the separator sheet, and when the heat-expandable capsule is thermally expanded, the expansion direction is set to the direction along the interface between the laminated separator sheets. And more reliable control. That is, the layers of the laminate in which the separator sheets are in close contact with each other are expanded two-dimensionally (in the plane direction) so that the expanding heat-expandable capsule cuts through the layers, and the state where there is no electrolytic solution in the heat generating portion and its surroundings is quickly obtained. Can be created. In addition, since the non-aqueous electrolytic solution secondary battery usually applies a constant pressure (usually "atmospheric pressure" + "0.05 to 0.1 MPa") in the stacking direction of the composite separator, it is thermally expandable. The capsule does not easily expand in the stacking direction of the separator sheet.
The above-mentioned "particle size of the heat-expandable capsule" is the average particle size of the heat-expandable capsule used. This average particle size is published by the manufacturer or distributor of thermally expandable capsules. If the average particle size announced by the manufacturer is unknown, the "particle size of the heat-expandable capsule" shall be the volume-based median diameter (d50).
As for the "hole diameter of the separator sheet", 20 holes (entrances of holes) observed on the surface of the separator sheet are randomly observed using an electron microscope, and each of the 20 holes on the surface of the separator sheet is observed. For each, the maximum value of the hole width in the direction perpendicular to the maximum radial direction is measured, and the 20 measured values are arithmetically averaged. The "maximum diameter" of a hole means this distance when the distance from one point on the inner circumference of the hole on the surface of the separator sheet to another point on the inner circumference is maximum. The pore size of the separator sheet is determined in a state where the separator sheet is dried.
　本発明に用いる熱膨張性カプセルの粒径は、１～２０μｍが好ましく、１～１５μｍがより好ましく、１～１２μｍがさらに好ましい。また、この粒径は１～１０μｍでもよく、１～５μｍでもよく、１～３μｍとすることも好ましい。また、セパレータシートの孔径は、１μｍ以下が好ましい。例えば、０．０１～１μｍとすることができ、０．０１～０．８μｍとしてもよく、０．０１～０．５μｍが好ましく、０．０２～０．２μｍがより好ましく、０．０３～０．１μｍがさらに好ましい。 The particle size of the heat-expandable capsule used in the present invention is preferably 1 to 20 μm, more preferably 1 to 15 μm, and even more preferably 1 to 12 μm. Further, the particle size may be 1 to 10 μm, may be 1 to 5 μm, and is preferably 1 to 3 μm. The pore size of the separator sheet is preferably 1 μm or less. For example, it can be 0.01 to 1 μm, may be 0.01 to 0.8 μm, preferably 0.01 to 0.5 μm, more preferably 0.02 to 0.2 μm, and 0.03 to 0. .1 μm is more preferable.
　続いて、本発明に用いる複合セパレータの構成材料について、好ましい形態を説明する。 Subsequently, a preferable form of the constituent material of the composite separator used in the present invention will be described.
＜セパレータシート＞
　複合セパレータを構成するセパレータシートとしては、非水電解液二次電池において通常用いられるセパレータを、本発明の効果を損なわない範囲で特に制限なく用いることができる。例えば、セパレータシートの構成材料として、多孔質のポリマー材料、無機材料、有機無機ハイブリッド材料またはガラス繊維などが挙げられる。セパレータシートの隙間の占める体積比率、すなわち気孔率は、２０％～９０％が好ましく、３５％～８０％がより好ましい。 <Separator sheet>
As the separator sheet constituting the composite separator, a separator usually used in a non-aqueous electrolyte secondary battery can be used without particular limitation as long as the effect of the present invention is not impaired. For example, examples of the constituent material of the separator sheet include a porous polymer material, an inorganic material, an organic-inorganic hybrid material, and glass fiber. The volume ratio occupied by the gaps in the separator sheet, that is, the porosity is preferably 20% to 90%, more preferably 35% to 80%.
　上記ポリマー材料としては、例えば、セルロース不織布、ポリエチレン、ポリプロピレンなどが挙げられ、これらを併用したセパレータシートを用いることもできる。孔径、気孔率や孔の閉塞温度などを変えた２種以上の微多孔フィルムを積層したものも好ましい。
　上記無機材料としては、例えば、アルミナ、二酸化珪素等の酸化物；　窒化アルミ、窒化珪素等の窒化物；　硫酸バリウム、硫酸カルシウム等の硫酸塩が挙げられる。 Examples of the polymer material include cellulose non-woven fabric, polyethylene, polypropylene and the like, and a separator sheet in which these are used in combination can also be used. It is also preferable to laminate two or more kinds of microporous films having different pore diameters, porosities, pore closing temperatures, and the like.
Examples of the inorganic material include oxides such as alumina and silicon dioxide; nitrides such as aluminum nitride and silicon nitride; and sulfates such as barium sulfate and calcium sulfate.
＜熱膨張性カプセル＞
　熱膨張性カプセルは、通常は、内部に発泡剤を含んだ熱可塑性樹脂で形成されている。発泡剤は目的の温度で膨張すれば特に制限されない。例えば、アゾ化合物、ニトロソ化合物、ヒドラジン誘導体、セミカルバジド化合物、テトラゾール化合物、イソシアネート化合物、重炭酸塩、炭酸塩、亜硝酸塩、水素化物、重炭酸ナトリウムと酸、過酸化水素とイースト菌、亜鉛粉末と酸などの化学発泡剤；並びに、ブタン、ペンタン、ヘキサン、ジクロルエタン、ジクロルメタン、フロン、空気、炭酸ガス、窒素ガスなどの物理発泡剤が挙げられる。
　本発明に用いる熱膨張性カプセルは、内部の低沸点液体が気化すること等により、内部圧力がカプセルを膨張させるのに充分な圧力となることで体積膨張するものが好ましい。体積膨張する温度を制御する方法としては、内部に封入する低沸点液体として、その沸点が目的の温度付近の液体を選択することにより制御できる。また、体積膨張をより素早く進行させるために、カプセルの外殻部分を所定温度以下に軟化点をもつ熱可塑性樹脂等により形成することも好ましい。カプセルの形成は、コアセルベーション法等の公知の方法等が採用できる。 <Thermal expansion capsule>
The heat-expandable capsule is usually formed of a thermoplastic resin containing a foaming agent inside. The foaming agent is not particularly limited as long as it expands at a target temperature. For example, azo compounds, nitroso compounds, hydrazine derivatives, semicarbazide compounds, tetrazole compounds, isocyanate compounds, bicarbonates, carbonates, nitrites, hydrides, sodium bicarbonate and acids, hydrogen peroxide and yeast, zinc powder and acids, etc. Chemical foaming agents; as well as physical foaming agents such as butane, pentane, hexane, dichloroethane, dichloromethane, freon, air, carbonate gas, nitrogen gas and the like.
The thermally expandable capsule used in the present invention is preferably one that expands in volume when the internal pressure becomes sufficient to expand the capsule due to vaporization of the low boiling point liquid inside. As a method of controlling the temperature of volume expansion, it can be controlled by selecting a liquid whose boiling point is close to a target temperature as the low boiling point liquid to be sealed inside. Further, in order to allow the volume expansion to proceed more quickly, it is also preferable to form the outer shell portion of the capsule with a thermoplastic resin or the like having a softening point at a predetermined temperature or lower. A known method such as a core selvation method can be adopted for forming the capsule.
　熱膨張性カプセルとしては、例えば日本フェライト株式会社製のエクスパンセル０５１ＤＵ、００７ＷＵ、０５３ＷＵ、０５３ＤＵ、０５４ＷＵ、０９１ＤＵ、０９１－０８０ＤＵ、０９１－１４０－ＤＵ、０９２－１２０ＤＵ、０９３－１２０ＤＵ、８２０ＷＵ、６４２ＷＵ、５５１ＷＵ、５５１ＤＵ、５５１－２０ＷＵ、５５１－２０ＤＵ、５５１－８０ＷＵ、５５１－８０ＤＵ、４６１ＷＵ、４６１ＤＵ、４６１－２０；　松本油脂製株式会社製のマイクロカプセルＦ－２０、Ｆ－３０、Ｆ－４０、Ｆ－５０、Ｆ－８０Ｓ、Ｆ－８２、Ｆ－８５、Ｆ－１００、ＦＮ－１００ＳＳＤなどが市販されている。これらは、共重合体の外殻と、その内部にある低沸点の炭化水素からなる発泡剤により構成されており、約７０℃から２００℃の間の所定の温度に達すると、外殻部分の軟化及び内容物の気化によって、自身の体積が、例えば４０～６０倍程度にまで膨張する。 Examples of the heat-expandable capsule include Expanders 051DU, 007WU, 053WU, 053DU, 054WU, 091DU, 091-080DU, 091-140-DU, 092-120DU, 093-120DU, 820WU, 642WU manufactured by Nippon Ferrite Co., Ltd. , 551WU, 551DU, 551-20WU, 551-20DU, 551-80WU, 551-80DU, 461WU, 461DU, 461-20; Microcapsules F-20, F-30, F-40, manufactured by Matsumoto Oil & Fat Co., Ltd. F-50, F-80S, F-82, F-85, F-100, FN-100 SSD and the like are commercially available. These are composed of an outer shell of a copolymer and a foaming agent composed of a low boiling point hydrocarbon inside the outer shell, and when a predetermined temperature between about 70 ° C. and 200 ° C. is reached, the outer shell portion of the outer shell portion. Due to softening and vaporization of the contents, its own volume expands to, for example, about 40 to 60 times.
　本発明に用いる熱膨張性カプセルは、熱膨張開始温度が、大気中（１気圧）における測定値よりも、非水電解液二次電池の電解液中（１気圧下に配された電解液中）における測定値が１０℃以上低いことが好ましい。これにより、非水電解液二次電池において、電池温度上昇に対する熱膨張応答性が高められ、電池異常が生じた際のシャットダウンを、より素早く行うことが可能となる。
　上記の非水電解液二次電池の電解液中において熱膨張開始温度が低下する場合、その要因としては、非水電解液に熱膨張マイクロカプセルが浸漬された際に、電解液に含まれる極性溶媒がカプセル壁を可塑化することが考えられる。電解液に含まれる極性溶媒の沸点が低いほど、熱膨張開始温度の低下がより顕在化する傾向にある。 In the thermally expandable capsule used in the present invention, the thermal expansion start temperature is higher in the electrolytic solution of the non-aqueous electrolytic solution secondary battery (in the electrolytic solution arranged under 1 atm) than the measured value in the atmosphere (1 atm). ) Is preferably 10 ° C. or higher. As a result, in the non-aqueous electrolyte secondary battery, the thermal expansion response to the rise in battery temperature is enhanced, and it becomes possible to shut down more quickly when a battery abnormality occurs.
When the thermal expansion start temperature drops in the electrolytic solution of the above-mentioned non-aqueous electrolytic solution secondary battery, the cause is the polarity contained in the electrolytic solution when the thermal expansion microcapsules are immersed in the non-aqueous electrolytic solution. It is conceivable that the solvent will plasticize the capsule wall. The lower the boiling point of the polar solvent contained in the electrolytic solution, the more the decrease in the thermal expansion start temperature tends to become more apparent.
　本発明に用いる複合セパレータは、平面視において、複合セパレータ全体の面積に占める、熱膨張性カプセルが配された部分の面積（熱膨張性カプセルをセパレータシートに水平投影した面積）の合計の割合が、５０％以下であることが好ましい。このように、熱膨張性カプセルをまばらに、事実上単層に、セパレータシートの間にまぶしても、本発明の目的の効果を得ることができる。また、この割合は、本発明の効果を奏する範囲で小さいほど好ましく、４０％以下がより好ましく、３０％以下がさらに好ましく、２０％以下とすることもできる。このように熱膨張性カプセルの使用量を減らしても、熱膨張性カプセルの熱膨張を二次元的に制御できる本発明の非水電解液二次電池では、素早いシャットダウン効果を実現することができる。 In the composite separator used in the present invention, in a plan view, the total ratio of the area of the portion where the heat-expandable capsule is arranged (the area of the heat-expandable capsule horizontally projected onto the separator sheet) to the total area of the composite separator is , 50% or less is preferable. As described above, even if the heat-expandable capsules are sprinkled sparsely, substantially in a single layer, between the separator sheets, the effect of the object of the present invention can be obtained. Further, this ratio is preferably as small as the range in which the effect of the present invention is exhibited, more preferably 40% or less, further preferably 30% or less, and may be 20% or less. Even if the amount of the heat-expandable capsule used is reduced in this way, the non-aqueous electrolyte secondary battery of the present invention capable of two-dimensionally controlling the thermal expansion of the heat-expandable capsule can realize a quick shutdown effect. ..
　本発明に用いる複合セパレータは、複合セパレータの周囲及び／又はその近傍において、セパレータシート同士が接着されている形態とすることが好ましい。このような形態とすることにより、熱膨張性カプセルが熱膨張した際などに外殻が破れてカプセルからガスが漏れた場合でも、セパレータシート同士の積層界面からのガスの散逸を遅らせることができ、シャットダウン状態のより安定的な維持にも寄与する。セパレータシート同士の接着は、ヒートシール等を施して行うことができ、複合セパレータの周囲に沿って、線状にヒートシール等を施すことが好ましい。 The composite separator used in the present invention is preferably in a form in which the separator sheets are adhered to each other around and / or in the vicinity of the composite separator. With such a form, even if the outer shell is torn and gas leaks from the capsule when the thermally expandable capsule is thermally expanded, the dissipation of gas from the laminated interface between the separator sheets can be delayed. It also contributes to the more stable maintenance of the shut down state. Adhesion between the separator sheets can be performed by applying heat sealing or the like, and it is preferable to apply heat sealing or the like linearly along the periphery of the composite separator.
　上記では、複合セパレータについて、非水電解液二次電池の正極と負極との間に配された状態に関して説明してきた。他方、上述した複合セパレータは、非水電解液二次電池用の複合セパレータとして、非水電解液二次電池に組み込む前の状態で独立して流通し得るものである。
　すなわち、本発明によれば、少なくとも２枚のセパレータシートで構成された積層体の層間に熱膨張性カプセルを挟持してなる非水電解液二次電池用複合セパレータが提供される。この非水電解液二次電池用複合セパレータは、電解液等に浸潤させていない乾燥状態であってもよく、電解液等に浸潤させて湿潤状態にあってもよい。また、本発明の非水電解液二次電池用複合セパレータのサイズは特に制限されない。サイズの大きな複合セパレータを作製し、非水電解液二次電池に組み込む際に、所望のサイズに切り取り、使用することもできる。 In the above, the composite separator has been described with respect to a state in which it is arranged between the positive electrode and the negative electrode of the non-aqueous electrolyte secondary battery. On the other hand, the above-mentioned composite separator can be independently distributed as a composite separator for a non-aqueous electrolyte secondary battery in a state before being incorporated into the non-aqueous electrolyte secondary battery.
That is, according to the present invention, there is provided a composite separator for a non-aqueous electrolyte secondary battery in which a heat-expandable capsule is sandwiched between layers of a laminate composed of at least two separator sheets. The composite separator for a non-aqueous electrolytic solution secondary battery may be in a dry state without being infiltrated with an electrolytic solution or the like, or may be in a wet state by being infiltrated with an electrolytic solution or the like. Further, the size of the composite separator for the non-aqueous electrolyte secondary battery of the present invention is not particularly limited. When a large-sized composite separator is produced and incorporated into a non-aqueous electrolyte secondary battery, it can be cut into a desired size and used.
　本発明の複合セパレータは、少なくとも２枚のセパレータシートを重ね合せる際に、所望の層間に、熱膨張性カプセルを略均一に分散して（まぶして）配することにより製造することができる。
　また、所望の層間に熱膨張性カプセルを配してなるセパレータシートの積層体を形成後、セパレータシート同士を、それらの周囲及び／又はその近傍において互いに接着することも好ましい。例えば、複合セパレータの周囲に沿って、１～１０ｍｍ幅のヒートシールを施して、隣接するセパレータシート同士を、複合セパレータの周囲に沿って互いに接着することができる。 The composite separator of the present invention can be produced by dispersing (sprinkling) heat-expandable capsules substantially uniformly between desired layers when at least two separator sheets are superposed.
It is also preferable that after forming a laminate of separator sheets formed by arranging heat-expandable capsules between desired layers, the separator sheets are adhered to each other around and / or in the vicinity thereof. For example, a heat seal having a width of 1 to 10 mm can be applied along the periphery of the composite separator to bond adjacent separator sheets to each other along the periphery of the composite separator.
　本発明の複合シートを用いて、非水電解液二次電池を製造することができる。すなわち本発明によれば、本発明の非水電解液二次電池用複合セパレータを正極と負極との間に配することを含む、非水電解液二次電池の製造方法が提供される。非水電解液二次電池用複合セパレータの、正極と負極との間への配設は、通常の非水電解液二次電池におけるセパレータの配設と同様にして行うことができる。 A non-aqueous electrolyte secondary battery can be manufactured using the composite sheet of the present invention. That is, according to the present invention, there is provided a method for manufacturing a non-aqueous electrolyte secondary battery, which comprises arranging the composite separator for the non-aqueous electrolyte secondary battery of the present invention between the positive electrode and the negative electrode. The arrangement of the composite separator for the non-aqueous electrolyte secondary battery between the positive electrode and the negative electrode can be performed in the same manner as the arrangement of the separator in the normal non-aqueous electrolyte secondary battery.
　本発明の非水電解液二次電池は、例えば、ノートパソコン、ペン入力パソコン、モバイルパソコン、電子ブックプレーヤー、携帯電話、コードレスフォン子機、ページャー、ハンディーターミナル、携帯ファックス、携帯コピー、携帯プリンター、ヘッドフォンステレオ、ビデオムービー、液晶テレビ、ハンディークリーナー、ポータブルＣＤ、ミニディスク、電気シェーバー、トランシーバー、電子手帳、電卓、メモリーカード、携帯テープレコーダー、ラジオ、バックアップ電源、メモリーカードなどの電子機器に搭載することができる。また、民生用として、自動車、電動車両、モーター、照明器具、玩具、ゲーム機器、ロードコンディショナー、時計、ストロボ、カメラ、医療機器（ペースメーカー、補聴器、肩もみ機など）などに搭載することができる。さらに、各種軍需用、宇宙用として用いることができる。また、太陽電池と組み合わせることもできる。 The non-aqueous electrolyte secondary battery of the present invention includes, for example, a notebook computer, a pen input computer, a mobile computer, an electronic book player, a mobile phone, a cordless phone slave unit, a pager, a handy terminal, a mobile fax, a mobile copy, a mobile printer, and the like. Headphones Stereo, video movies, LCD TVs, handy cleaners, portable CDs, mini discs, electric shavers, transceivers, electronic notebooks, calculators, memory cards, portable tape recorders, radios, backup power supplies, memory cards, and other electronic devices. Can be done. For consumer use, it can be installed in automobiles, electric vehicles, motors, lighting equipment, toys, game equipment, road conditioners, watches, strobes, cameras, medical equipment (pacemakers, hearing aids, shoulder massagers, etc.). Furthermore, it can be used for various munitions and space. It can also be combined with a solar cell.
　以下に、実施例に基づき本発明についてさらに詳細に説明する。なお、本発明がこれにより限定して解釈されるものではない。 Hereinafter, the present invention will be described in more detail based on Examples. It should be noted that the present invention is not construed as being limited thereto.
［非水電解液の調製］
　エチレンカーボネートを４０質量％、エチルメチルカーボネートを６０質量％含有する非水溶媒中に、リチウム塩としてＬｉＰＦ６を１Ｍ濃度となるように溶解し、非水電解液を調製した。 [Preparation of non-aqueous electrolyte solution]
A non-aqueous electrolytic solution was prepared by dissolving LiPF 6 as a lithium salt at a concentration of 1 M in a non-aqueous solvent containing 40% by mass of ethylene carbonate and 60% by mass of ethyl methyl carbonate.
［正極活物質層形成材料の調製］
　正極活物質としてニッケルマンガン酸リチウム（ＬｉＮｉ０．５Ｍｎ１．５Ｏ４）を８５質量％、導電助剤としてカーボンブラックを７質量％、結着剤としてＰＶＤＦ（ポリフッ化ビニリデン）を８質量％含有する組成物を調製し、正極活物質層形成材料とした。 [Preparation of positive electrode active material layer forming material]
85% by mass of lithium nickel manganate (LiNi 0.5 Mn 1.5 O 4 ) as the positive electrode active material, 7% by mass of carbon black as the conductive auxiliary agent, and 8% by mass of PVDF (polyvinylidene fluoride) as the binder. The composition to be contained was prepared and used as a positive electrode active material layer forming material.
［負極活物質層形成材料の調製］
　負極活物質としてＧｒ（天然黒鉛）を９２質量％、結着剤としてＰＶＤＦを８質量％含有する組成物を調製し、負極活物質層形成材料とした。 [Preparation of negative electrode active material layer forming material]
A composition containing 92% by mass of Gr (natural graphite) as the negative electrode active material and 8% by mass of PVDF as the binder was prepared and used as a negative electrode active material layer forming material.
［複合セパレータ］
　縦５ｃｍ×横６ｃｍ×厚み２０μｍのサイズで、孔径１μｍ以下、熱溶融温度が１６０℃のポリプロピレン製セパレータシート２枚を用意した。２枚のセパレータシート間に、熱膨張性カプセルとしてマツモトマイクロスフェア－ＦＮ－１００ＳＳＤ（松本油脂製薬社製、熱膨張開始温度が大気中（１気圧下）で１２０～１３０℃、平均粒子径６～１１μｍ（メーカー公表値））を略均一にまぶして単層に配し、熱膨張性カプセルとそれを挟持する２枚のセパレータシートからなる複合セパレータを調製した。この複合セパレータは、平面視において、複合セパレータ全体の面積に占める、熱膨張性カプセルが配された部分の面積の合計の割合が、４０～４８％であった。
　得られた複合セパレータを実施例２の非水電解液二次電池に用いた。また、得られた複合セパレータを、ヒートシーラーを用いてその周囲４辺を５ｍｍ幅でヒートシールしたものを実施例１の非水電解液二次電池に用いた。また、熱膨張性カプセルを挟持させずに２枚のセパレータシートを積層し、この積層体の周囲４辺を５ｍｍ幅でヒートシールしたものを比較例の非水電解液二次電池に用いた。非水電解液二次電池の作製について以下に説明する。 [Composite separator]
Two polypropylene separator sheets having a size of 5 cm in length × 6 cm in width × 20 μm in thickness, a hole diameter of 1 μm or less, and a hot melting temperature of 160 ° C. were prepared. Between the two separator sheets, as a heat-expandable capsule, Matsumoto Microsphere-FN-100 SSD (manufactured by Matsumoto Yushi Pharmaceutical Co., Ltd., the thermal expansion start temperature is 120 to 130 ° C in the atmosphere (under 1 atm), the average particle size is 6 to 6 to 11 μm (value published by the manufacturer) was sprinkled substantially uniformly and arranged in a single layer to prepare a composite separator composed of a heat-expandable capsule and two separator sheets sandwiching the same. In the plan view of this composite separator, the ratio of the total area of the portion where the heat-expandable capsules were arranged to the total area of the composite separator was 40 to 48%.
The obtained composite separator was used in the non-aqueous electrolyte secondary battery of Example 2. Further, the obtained composite separator was heat-sealed with a width of 5 mm on four sides around the composite separator using a heat sealer, and used in the non-aqueous electrolyte secondary battery of Example 1. Further, two separator sheets were laminated without sandwiching the heat-expandable capsule, and the four sides around the laminate were heat-sealed with a width of 5 mm, which was used for the non-aqueous electrolyte secondary battery of the comparative example. The production of the non-aqueous electrolyte secondary battery will be described below.
［非水電解液二次電池の作製］
　図５に示すラミネート型セル電池（ラミセル電池）を下記の通り作製した（図５は、複合セパレータが熱膨張性カプセルを有する形態を模式的に示す。）。
　上記正極活物質層形成材料を、アルミ集電箔（縦３．８ｃｍ×横５．３ｃｍ×厚み８０μｍ）上に塗布し、乾燥後プレスして、正極を作製した。また、上記負極活物質層形成材料を、銅集電箔（縦４ｃｍ×横５．５ｃｍ×厚み８０μｍ）上に塗布し、乾燥後プレスして、負極を作製した。上記複合セパレータを正極と負極との間に挟んだ状態で、Ａｌラミネートフィルムで作製した袋にいれ、電解液を注入し、真空封止してラミセル電池を作製した。得られたラミセル電池をＳＵＳ板（縦５ｃｍ×横７ｃｍ×厚み１ｍｍ）で挟み、大気圧＋０．０５ＭＰａで拘束し、下記試験に用いた。 [Manufacturing of non-aqueous electrolyte secondary battery]
The laminated cell battery (Lamicelle battery) shown in FIG. 5 was produced as follows (FIG. 5 schematically shows a form in which the composite separator has a heat-expandable capsule).
The positive electrode active material layer forming material was applied onto an aluminum current collector foil (length 3.8 cm × width 5.3 cm × thickness 80 μm), dried and pressed to prepare a positive electrode. Further, the negative electrode active material layer forming material was applied onto a copper current collector foil (length 4 cm × width 5.5 cm × thickness 80 μm), dried and pressed to prepare a negative electrode. With the composite separator sandwiched between the positive electrode and the negative electrode, the battery was placed in a bag made of an Al laminated film, an electrolytic solution was injected, and the battery was vacuum-sealed to prepare a lamicelle battery. The obtained lamicelle battery was sandwiched between SUS plates (length 5 cm × width 7 cm × thickness 1 mm), restrained at atmospheric pressure + 0.05 MPa, and used in the following test.
［試験例］　シャットダウン性能の評価
　上記で作製した非水電解液二次電池（ラミセル電池）を用いて、電池温度上昇時にシャットダウン性能を下記のように評価した。
　５０℃に設定したホットプレート上に電池を静置し、ホットプレートの温度を５℃／分の昇温速度で上昇させながら、１ｋＨｚの交流法で内部抵抗を測定した。５０℃の抵抗値（Ω）を「１」としたとき、温度上昇に伴う抵抗値の上昇率を調べた。
　結果を下表に示す。 [Test Example] Evaluation of Shutdown Performance Using the non-aqueous electrolyte secondary battery (Lamicelle battery) prepared above, the shutdown performance was evaluated as follows when the battery temperature rose.
The battery was allowed to stand on a hot plate set at 50 ° C., and the internal resistance was measured by an AC method of 1 kHz while raising the temperature of the hot plate at a heating rate of 5 ° C./min. When the resistance value (Ω) at 50 ° C. was set to “1”, the rate of increase in the resistance value with the temperature rise was investigated.
The results are shown in the table below.
Figure JPOXMLDOC01-appb-T000001
  
Figure JPOXMLDOC01-appb-T000001
  
　上記表に示されるように、本発明の複合セパレータを用いることにより、温度上昇がより低い状態でもシャットダウン機能が発現することがわかる。また、複合セパレータの周囲をシールしておくことにより、さらに低温域においてシャットダウン機能が発現し始めることもわかった。
　また、高温（１８０℃以上）によってセパレータシートの熱溶融状態が進行してセパレータシート自体では高度なシャットダウン状態を維持できない状態となっても、本発明の複合セパレータを用いることにより、上記の高温状態で、むしろシャットダウン状態をさらに高めることができることもわかった。これは、２枚のセパレータシートの熱溶融状態がかなり進行しても、これらのシートはその間に挟まれて存在する熱膨張したカプセル（樹脂）ないしガスにより保持され、２枚の熱溶融セパレータシートと熱膨張したカプセルないしガスとが一体に作用して、安定的なシャットダウンに寄与しているものと推定される。 As shown in the above table, it can be seen that the shutdown function is exhibited even when the temperature rise is lower by using the composite separator of the present invention. It was also found that by sealing the periphery of the composite separator, the shutdown function begins to appear even in the low temperature range.
Further, even if the hot melting state of the separator sheet progresses due to a high temperature (180 ° C. or higher) and the separator sheet itself cannot maintain a high shutdown state, the above-mentioned high temperature state can be obtained by using the composite separator of the present invention. So, I also found that the shutdown state can be further enhanced. This is because even if the hot-melted state of the two separator sheets progresses considerably, these sheets are held by the thermally expanded capsule (resin) or gas existing between them, and the two hot-melted separator sheets are held. It is presumed that the heat-expanded capsule or gas acts together to contribute to a stable shutdown.
　本発明をその実施態様とともに説明したが、我々は特に指定しない限り我々の発明を説明のどの細部においても限定しようとするものではなく、添付の請求の範囲に示した発明の精神と範囲に反することなく幅広く解釈されるべきであると考える。 Although the present invention has been described with its embodiments, we do not intend to limit our invention in any detail of the description unless otherwise specified, and contrary to the spirit and scope of the invention set forth in the appended claims. I think that it should be widely interpreted without.
　本願は、２０１９年１０月３０日に日本国で特許出願された特願２０１９－１９７７４７に基づく優先権を主張するものであり、これはここに参照してその内容を本明細書の記載の一部として取り込む。 The present application claims priority based on Japanese Patent Application No. 2019-197747 filed in Japan on October 30, 2019, which is referred to herein and is described herein. Incorporate as a part.
Ｃ　正極
１　正極導電材（集電体）
２　正極活物質層
Ａ　負極
３　負極導電材（集電体）
４　負極活物質層
５　非水電解液
６　動作機構
７　回路配線
９　セパレータ
１０　リチウムイオン二次電池
１２　セパレータ
１４　正極シート
１６　負極シート
１８　負極集電体を兼ねる外装缶
２０　絶縁板
２２　封口板
２４　正極集電体
２６　ガスケット
２８　圧力感応弁体
３０　電流遮断素子
１００　有底筒型形状リチウムイオン二次電池
４０　複合セパレータ
４１、４２　セパレータシート
４３　熱膨張性カプセル（膨張前後）
４４　正極活物質層
４５　アルミ集電箔
４６　負極活物質層
４７　銅集電箔
４８　Ａｌラミネートフィルム
４９、５０　回路配線 C Positive electrode 1 Positive electrode conductive material (current collector)
2 Positive electrode active material layer A Negative electrode 3 Negative electrode conductive material (current collector)
4 Negative electrode active material layer 5 Non-aqueous electrolyte 6 Operating mechanism 7 Circuit wiring 9 Separator 10 Lithium ion secondary battery 12 Separator 14 Positive electrode sheet 16 Negative electrode sheet 18 Exterior can that doubles as a negative electrode current collector 20 Insulation plate 22 Seal plate 24 Positive electrode collection Electric body 26 Gasket 28 Pressure sensitive valve body 30 Current blocking element 100 Bottomed tubular shape Lithium ion secondary battery 40 Composite separator 41, 42 Separator sheet 43 Thermally expandable capsule (before and after expansion)
44 Positive electrode active material layer 45 Aluminum current collector foil 46 Negative electrode active material layer 47 Copper current collector foil 48 Al Laminated film 49, 50 Circuit wiring

Claims (10)

  1. 　正極と、負極と、該正極と該負極との間に配された複合セパレータとを有する非水電解液二次電池であって、
    　前記複合セパレータは、少なくとも２枚のセパレータシートで構成された積層体の層間に熱膨張性カプセルを挟持してなる、非水電解液二次電池。     A non-aqueous electrolytic solution secondary battery having a positive electrode, a negative electrode, and a composite separator arranged between the positive electrode and the negative electrode.
    The composite separator is a non-aqueous electrolyte secondary battery in which a heat-expandable capsule is sandwiched between layers of a laminate composed of at least two separator sheets.
  2. 　前記非水電解液二次電池中において、前記熱膨張性カプセルの熱膨張開始温度が、該熱膨張性カプセルを挟持する前記セパレータシートの熱溶融温度よりも５℃以上低い、請求項１に記載の非水電解液二次電池。 The first aspect of the non-aqueous electrolyte secondary battery, wherein the thermal expansion start temperature of the heat-expandable capsule is 5 ° C. or more lower than the heat-melting temperature of the separator sheet sandwiching the heat-expandable capsule. Non-aqueous electrolyte secondary battery.
  3. 　前記熱膨張性カプセルの粒径が、該熱膨張性カプセルを挟持する前記セパレータシートの孔径の１．５倍以上である、請求項１又は２に記載の非水電解液二次電池。 The non-aqueous electrolyte secondary battery according to claim 1 or 2, wherein the particle size of the heat-expandable capsule is 1.5 times or more the pore size of the separator sheet sandwiching the heat-expandable capsule.
  4. 　前記熱膨張性カプセルの熱膨張開始温度が、大気中における測定値よりも、前記電解液中における測定値が１０℃以上低い、請求項１～３のいずれか１項に記載の非水電解液二次電池。 The non-aqueous electrolytic solution according to any one of claims 1 to 3, wherein the thermal expansion start temperature of the thermally expandable capsule is lower than the measured value in the atmosphere by 10 ° C. or more in the electrolytic solution. Secondary battery.
  5. 　前記複合セパレータは、平面視において、該複合セパレータ全体の面積に占める、熱膨張性カプセルが配された部分の面積の合計の割合が、５０％以下である、請求項１～４のいずれか１項に記載の非水電解液二次電池。 The composite separator is any one of claims 1 to 4, wherein the ratio of the total area of the portion where the heat-expandable capsule is arranged to the total area of the composite separator is 50% or less in a plan view. Non-aqueous electrolyte secondary battery as described in the section.
  6. 　前記非水電解液二次電池において、前記複合セパレータは、セパレータシートの積層方向に加圧された状態にある、請求項１～５のいずれか１項に記載の非水電解液二次電池。 The non-aqueous electrolyte secondary battery according to any one of claims 1 to 5, wherein the composite separator is in a state of being pressurized in the stacking direction of the separator sheets in the non-aqueous electrolyte secondary battery.
  7. 　前記非水電解液二次電池において、前記複合セパレータを構成するセパレータシートが微多孔膜であり、前記複合セパレータを構成するセパレータシート同士が電解液の作用により密着している、請求項１～６のいずれか１項に記載の非水電解液二次電池。 In the non-aqueous electrolytic solution secondary battery, claims 1 to 6 wherein the separator sheet constituting the composite separator is a microporous membrane, and the separator sheets constituting the composite separator are in close contact with each other by the action of the electrolytic solution. The non-aqueous electrolyte secondary battery according to any one of the above items.
  8. 　前記複合セパレータの周囲及び／又はその近傍において、セパレータシート同士が接着されている、請求項１～７のいずれか１項に記載の非水電解液二次電池。 The non-aqueous electrolyte secondary battery according to any one of claims 1 to 7, wherein the separator sheets are adhered to each other around and / or in the vicinity of the composite separator.
  9. 　少なくとも２枚のセパレータシートで構成された積層体の層間に熱膨張性カプセルを挟持してなる、非水電解液二次電池用複合セパレータ。 A composite separator for a non-aqueous electrolyte secondary battery, in which a heat-expandable capsule is sandwiched between layers of a laminate composed of at least two separator sheets.
  10. 　請求項９に記載の非水電解液二次電池用複合セパレータを正極と負極との間に配することを含む、非水電解液二次電池の製造方法。 A method for manufacturing a non-aqueous electrolyte secondary battery, which comprises arranging the composite separator for a non-aqueous electrolyte secondary battery according to claim 9 between a positive electrode and a negative electrode.
PCT/JP2020/040485 2019-10-30 2020-10-28 Nonaqueous electrolyte secondary battery, separator used for same, and method for producing nonaqueous electrolyte secondary battery WO2021085487A1 (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
JP2021553660A JP7314296B2 (en) 2019-10-30 2020-10-28 Non-aqueous electrolyte secondary battery, separator used therein, and method for manufacturing non-aqueous electrolyte secondary battery
US17/699,186 US20220209362A1 (en) 2019-10-30 2022-03-21 Non-aqueous electrolytic solution secondary battery, separator formed of non-aqueous electrolytic solution secondary battery, and method of manufacturing non-aqueous electrolytic solution secondary battery
JP2023114337A JP2023134622A (en) 2019-10-30 2023-07-12 Non-aqueous electrolyte secondary battery, separator to be used for the same, and manufacturing method for non-aqueous electrolyte secondary battery

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2019197747 2019-10-30
JP2019-197747 2019-10-30

Related Child Applications (1)

Application Number Title Priority Date Filing Date
US17/699,186 Continuation US20220209362A1 (en) 2019-10-30 2022-03-21 Non-aqueous electrolytic solution secondary battery, separator formed of non-aqueous electrolytic solution secondary battery, and method of manufacturing non-aqueous electrolytic solution secondary battery

Publications (1)

Publication Number Publication Date
WO2021085487A1 true WO2021085487A1 (en) 2021-05-06

Family

ID=75716308

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2020/040485 WO2021085487A1 (en) 2019-10-30 2020-10-28 Nonaqueous electrolyte secondary battery, separator used for same, and method for producing nonaqueous electrolyte secondary battery

Country Status (3)

Country Link
US (1) US20220209362A1 (en)
JP (2) JP7314296B2 (en)
WO (1) WO2021085487A1 (en)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006002134A (en) * 2004-05-19 2006-01-05 Sekisui Chem Co Ltd Thermally expansible microcapsule and method for producing the same
JP2008226807A (en) * 2007-02-14 2008-09-25 Nissan Motor Co Ltd Non-aqueous electrolyte secondary battery
JP2013004305A (en) * 2011-06-16 2013-01-07 Toyota Motor Corp Secondary battery
WO2018086095A1 (en) * 2016-11-14 2018-05-17 上海顶皓新材料科技有限公司 Multi-layered composite functional separator for lithium-ion battery

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4686182B2 (en) * 2004-12-29 2011-05-18 恵和株式会社 Battery separator, manufacturing method, and secondary battery
JP2010086728A (en) * 2008-09-30 2010-04-15 Toyota Motor Corp Lithium ion battery

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006002134A (en) * 2004-05-19 2006-01-05 Sekisui Chem Co Ltd Thermally expansible microcapsule and method for producing the same
JP2008226807A (en) * 2007-02-14 2008-09-25 Nissan Motor Co Ltd Non-aqueous electrolyte secondary battery
JP2013004305A (en) * 2011-06-16 2013-01-07 Toyota Motor Corp Secondary battery
WO2018086095A1 (en) * 2016-11-14 2018-05-17 上海顶皓新材料科技有限公司 Multi-layered composite functional separator for lithium-ion battery

Also Published As

Publication number Publication date
JP2023134622A (en) 2023-09-27
US20220209362A1 (en) 2022-06-30
JP7314296B2 (en) 2023-07-25
JPWO2021085487A1 (en) 2021-05-06

Similar Documents

Publication Publication Date Title
JP5328034B2 (en) Electrochemical element separator, electrochemical element and method for producing the same
KR101105748B1 (en) Separator for electrochemical device and method for producing same, and electrochemical device and method for manufacturing same
JP5879018B2 (en) Electrochemical element and method for producing the same
JP5093882B2 (en) Electrochemical element separator, electrochemical element and method for producing electrochemical element
JP4173674B2 (en) Electrochemical device module
JP5241314B2 (en) Laminated non-aqueous secondary battery
JP5882549B1 (en) Nonaqueous secondary battery separator, method for producing the same, and nonaqueous secondary battery
JP2002208442A (en) Electrochemical device
JPH09161757A (en) Multilayered nonaqueous electrolyte secondary battery
JP2008027839A (en) Porous membrane with liner, method of manufacturing porous membrane, and method of manufacturing lithium secondary battery
KR20140071951A (en) Heat resistant porous membrane, separator for nonaqueous cell, and nonaqueous cell
JP2007294437A (en) Separator for electrochemical cell, and lithium secondary battery
KR20150126367A (en) Non-aqueous electrolyte secondary battery
JP2008066094A (en) Separator for battery, and lithium secondary battery
JP2008097991A (en) Electric storage device
JP2016181324A (en) Separator for electrochemical device
JP2014007089A (en) Separator for electrochemical element, and electrochemical element
JP2004111157A (en) Secondary battery and its manufacturing method
JP2011100602A (en) Nonaqueous electrolyte battery
JP2008004442A (en) Separator for lithium secondary battery, and lithium secondary battery
JPWO2012053286A1 (en) Electrochemical element separator and method for producing the same, electrochemical element electrode and electrochemical element
KR101882920B1 (en) Capsule type foaming agents, coating composition for separator comprising the same, the separator, and secondary cell comprising the same
WO1999034469A1 (en) Lithium ion secondary battery
JP5804712B2 (en) Nonaqueous electrolyte secondary battery
JP2003272595A (en) Manufacturing method for electrochemical device, manufacturing equipment, and electrochemical device

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 20880886

Country of ref document: EP

Kind code of ref document: A1

ENP Entry into the national phase

Ref document number: 2021553660

Country of ref document: JP

Kind code of ref document: A

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 20880886

Country of ref document: EP

Kind code of ref document: A1